I just returned from SXSW Interactive (SXSWi) and was blown away by the scale of the festival. There were more than 15,000 people in attendance, looking to expand their knowledge around the Web, social and mobile (for the most part).

It would be impossible for me to summarize the entire festival for you, so here's the "what was trending" version with what you might have missed in the stream:

#1 Location-Based Services Stole the Show

For the first time in many months, something made more noise than Twitter among the Web crowd, namely Foursquare and Gowalla. While there are a bunch of location-based services (LBS) out there, SXSW Interactive was a showdown between Foursquare and Gowalla.

SXSWi was the perfect venue for LBS to take off, due to its geographic focus, large number of events and high concentration of early-adopters. I saw more people checking in on Foursquare than tweeting. Foursquare hit a new usage record at the show, with more than 347,000 check-ins in a day.

Every inch of Austin was checked-in to on one or both of these services during SXSWi, with attendees trying to take over mayorships on any piece of fictional real estate they could find. There's still some question over business models and monetization, but with usage levels like this, there remains a lot of potential.

Gowalla (a similar service) made a fair impact at the festival, but was overshadowed a bit by Foursquare's daily four square games, custom SXSWi badges, heaps of swag, and its star-studded party with the likes of Ashton Kutcher.

While there was a lot of buzz for Foursquare, you really need massive user adoption to make this stuff work. At a show with 15,000+ people, you're bound to have a friend nearby. To really make LBS stick, locations will have to start offering up incentives to people who check in (the most logical extension to all this stuff).

To quote Gary Vaynerchuk's keynote (see #3): "Why the heck would I check in somewhere? If someone gives you a f**king beer for checking in, you're going to check in."

It's true, once businesses start rewarding customers for their check-ins, services like Foursquare are going to explode in popularity (which is what happended when Twitter followers started to get hookups). I wouldn't be surprised to see Foursquare owned by somebody else by the time SXSW rolls around next year.

#2 Private Parts

The more people share online - such as where they're having lunch or who they're hanging out with at SXSWi - the more privacy becomes an issue.

Danah Boyd, Social Media Researcher at Microsoft Research New England, delivered the opening remarks at SXSWi, quickly launching into a mild attack on Google Buzz and Facebook for their recent, well-reported missteps regarding privacy. "Just because something is publicly accessible, it doesn't mean people want it publicized," said Boyd.

As more and more people take to lifestreaming, there's mounting concerns over the sharing of sensitive information. Boyd says she's never met anyone that really knew what their privacy settings were on any social site they use.

While on one hand brands want to open up the lines of communication with customers, they also need to consider any potential privacy implications.

There's a great write-up on Danah's keynote on Techcrunch here.

#3 Gary Vaynerchuk's Keynote

There had to be more than 1,000 people there to hear Gary Vaynerchuk have a conversation with the crowd. Gary is all about connecting with people on a personal level. He stood at the door and personally thanked everyone for attending the keynote (did I mention there were about 1,000 people in there?).

Gary has a no-BS approach to his presentations that reallly make you just want to watch him again. Bottom line? Most companies don't care and consumers know it. When companies even show they care a little, they get rewarded (Zappos is a perfect example).

For a great summary of the keynote, check out Andrew Mager's post on ZDNet. And in case you're wondering, he's got a mean four square serve too.

For a more coloful view into the keynote, you can watch it here. The quality's a bit shaky, but you can still get the content. Keep in mind, Gary's a brilliant speaker, but he does have a potty mouth (in case you get offended by profanity).

#4 Twitter Launches @anywhere

While Foursquare and Gowalla drove the buzz, Twitter still managed to get its share of the lime light. Unfortunately, a good part of the chatter revolved around how boring the keynote was, causing about half the room to leave before it was over.

Dissappointing keynote asside, the launch of @anywhere was significant. @anywhere is a new framework that enables developers to integrate the Twitter experience into their sites. Early @Anywhere partners include eBay, Amazon, Salesforce.com, Bing, Yahoo! and MSNBC.

For the full scoop on @anywhere, check out the official Twitter blog.

#5 Can You Digg It?

Almost launched in the midst of SXSWi was the announcement that Digg is getting a major overhaul. Digg CEO Jay Adelson made the announcement at the "Bigg Digg Shindigg" (love the name). The overhaul will include personalized feeds and the return of the Digg leaderboard. You can learn more about the new version (and sign up for the beta) at http://new.digg.com.

#6 QR Codes

There were QR codes (Quick Response code technology) on everything at SXSWi, from everyone's name badges to the fleet of Chevys on display. QR codes, a special type of bar code, are becoming more prevalent in advertising and product packaging. They provide an added way for consumers to interact with content, typically through a mobile device.

For example, if you used one of the QR readers (like I-Nigma for the iPhone) to scan an attendees badge at SXSWi, you were able to save the person's information. It was a cool way to exchange information, despite the experience being a bit slow. Look for QR codes to show up more and more (more on the SXSWi QR stuff here).

Checking Out

In conclusion, when all the hype dies down, everyone will remember this year's SXSWi as the kickoff of LBS for the masses. If last year was the year of "What are you doing?", this year will certainly be the year of the "Check-in".

Were you there? What was your favorite part of SXSWi? Let us know.

(Image Credits: Danah Boyd Art by amanichannel)