I've just taken the plunge and sold my Canon 550D that I had as backup for shooting wedding video.
I decided to go for a Canon 600D instead, I think the following features over the Canon 550D are for me well worth the upgrade. Overall the deal was cash neutral as the price for the Canon 550D covered the cost of the Canon 600D.
1) Rotating LCD screen - definitely a real bonus for shooting video and Live view.
2) Video crop mode - far more flexible feature on Canon 600D compared to the Canon 550D
3) Wireless flash control built in - will be very useful and save needing to use the Canon ST-E2
Other features that are available on the Canon 60D such as faster frame rate, higher Raw buffer are not things that I would need. The additional focus points that the Canon 60D offers compared to the Canon 600D/Canon 550D are of no use to me as I primarily only use the central focus point anyway.
Whats in the Canon 600D box - coming soon!