Bloc Party will be performing on 'Later...with Jools Holland'tomorrow (Friday 25th May) alongside LCD Soundsystem, Wilco and Joan Armatrading. This goes out on BBC2 at 11:35pm, but check back for some YouTube action if you live outside the UK. Here's a video interview with Kele and Matt recorded in the Later... studios.
The band also appeared on this show way back in November 2004 - making their first television performance in front of an audience largely oblivious to the joys of Bloc Party. Read a pre-show interview here, and watch their fresh-faced performances of 'Helicopter' and 'Like Eating Glass':
Helicopter (Live on Jools Holland, 19.11.04)
Like Eating Glass (Live on Jools Holland, 19.11.04)
 Bloc Party have just announced some special guests for their December arena dates: The Cribs, The Rakes and Foals!
[edit #2] Check out a video interview with Matt for Punkrockvids and an interview with Gordy in Montreal.