2 hours left to join Product People Club: http://productpeople.club/join/ pic.twitter.com/aJtVpvD09L
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Scarcity always helps, but the more pragmatic reason is I like to be around to personally welcome new members. 
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.