Over 300 people from the UK Internet community got together to mark the end of IPv4 at the London Transport Museum and promote the adoption of IPv6.
Ed Vaizey MP did an introductory speech followed by an review of IPv4 by Prof Peter Kirstein (UCL) and IPv6 by Simon McCalla (Nominet). After a short panel debate on IPv6 readiness there was a mock handover of 185/8 from IANA to RIPE NCC. Finally, Gary Feldman performed his RIPE55 song "The day the routers died" (a parody of American Pie).
I took a few photos and some video. The Internet survived unharmed (although I did turn it off at one point, sorry if you were using it at the time).