Jeff Utecht talks about how Foursquare exploded across a school campus. Explains that we can not control our communities and the tools they use. Instead we have to embrace. Great ideas of how to use check-in services as motivators and simple rewards for students being present when/where it matters. Provides great statistics to back up the claims put forth.
don't get me wrong. i love my twitter pln. but sometimes there are threads i could do without - like the recent soccer world cup conversations that went on for...a long time. or the constant "i checked in at ...on foursquare!" posts that i couldn't care less about. declutter will hide whatever keywords you choose, using a bookmarklet, so your stream can focus on what's important to you. sorry if that sounds like an advert, but i've been waiting for a tool like this!