On the heels of hi5's OpenSocial launch, this Sunday, the 6th of April, BT is hosting an OpenSocial Hackathon at BT Centre in London. This is an ideal opportunity to get started building apps with OpenSocial, or come and get a hand with an app you've already built. In addition, you'll be able to talk with engineers from Hyves, MySpace, Netlog, studiVZ, XING, and Google.

The event will kick off at 11:00am, though doors will open at 10:00am with a light breakfast. Full details are available here, or you can directly RSVP here.