Rust 1.0 is being released on May 15, and letting it go unmarked would be criminal.
I think it'd be great if we had a hour or so of lightning talks, of maybe 5-20 minutes each (some ideas (http://www.reddit.com/r/rust/comments/32sdrp/rust_meetup_in_london/cqe9t2k)): if you're interested be sure to send me a message. Speakers will get a t-shirt (http://users.rust-lang.org/t/rust-1-0-launch-event-details-action-required-for-event-organizers/1025) (assuming availability/sizes etc, I can't guarantee it but I'll try my hardest)!
Atlassian will graciously be providing pizza and drinks. Use the side entrance on Wynyard St rather than Atlassian's nominal address. Atlassians will be around between 6 and 6:15 to provide access (lifts need a swipe).
(Timezones and scheduling constraints make this meetup 3 days after the release.)