I get a lot of questions about new Speedlites. Especially the 580EX II.
The latest bits of information I have received have said the new flagship flash has been in development for some time and various prototypes exist. There were some issues with earlier prototypes and some redesign was needed.
Another bit of information suggested both the 430 and 580 would be updated at the same time. They may also get new model numbers beyond a version III. A new 580 prototype is said to have a higher guide number, so the model number would reflect that if chosen for production.
No word on whether or not a video light would be built into either like the 320EX.
I would only expect a flagship Speedlite announcement with or around the announcement of a higher end body.