There's an intersting news article regarding photography at the London Eye in this week's AP.

Strangely non of us at the recent London Meet had any problems when photographing around the Eye despite the prevalence of (D)SLRs and a couple of tripods being carried. Pam and I had to surrender up our tripods for the actual flight but had no problems with the rest of our kit. I know this was during daylight hours but I was happily able to use my tripod on the Millennium Bridge with no problems as it got dark.