SocialPicks is incorporated in Delaware. To attend YC's SFP '07, I applied for a 4-month TN Visa at a port of entry (Vancouver airport) en route to Cambridge. More info can be found at http://travel.state.gov/visa/temp/types/types_1274.html
And hey, starting up in Vancity now may leave you with JUST enough time to exit in order to afford the hockey tickets for the 2010 Winter Olympics ;)...