Jim wrote a great post on Foursquare, sxsw’s most talked about location-based mobile application that lets users check-in to see where their friends are, share tips and develop loyalty to different venues. What you might be surprised to know, is that even celebrities—yes those people avoiding crowds and cameras and often trying to remain anonymous—are checking in on Foursquare so that all their followers know exactly where they are.

When I landed in Austin I was reading through new tweets on my phone and saw that Ashton Kutcher had checked in at the Austin airport 6 minutes before. This was the first time I was ever coincidentally checked in to the same place as ANYONE that I follow, much less a celebrity, so I may have paused at the gate departing to LA for a minute or two, but no luck.

I thought that would be the beginning and end of my celebrity almost run-ins fueled by social media, but I guess you never know what Twitter can spark when you’re at sxsw. On Wednesday night a few PepsiCo employees were enjoying one of the first concerts of the music festival. We were in the back of this low-key concert in a hotel bar and again I was flipping through tweets on my phone when I saw that Perez Hilton, celebrity blogger and now a celebrity himself, had just tweeted that he was at the same hotel and concert. I mentioned it to my coworkers and we debated the degree of stalkers that would make us, but decided to walk around just in case. Ten steps later we saw Perez sitting with two friends enjoying the show. We shamelessly asked for a photo and it was nice to meet him, but more so I thought it was so interesting the way social media can even bring celebrities and fans together via their shared check-ins.