AMD 5 Series GPUs Support 3D Blu-ray
I haven't had a chance to go through AMD's driver release notes to find out when they snuck frame sequential 3D Blu-ray support in for their 5 series cards, but I can can confirm that it works, at least for the 5550. This page indicates that the whole lineup is supported, starting with the 5450. So if you have a modern AMD GPU and a HDMI 1.4 HDTV looks like you're good to go - too bad there's not more content.
Had an interesting conversation with Shane Parfitt today that brought up some information that wasn't on the 3DBD support page. Probably the most important, is that MVC decoding is not handled by the GPU on 5xxx cards, which means that a competent CPU is required to get decent playback. The second, and something that many have suspected because AMD released 67xx which are essentially rebranded 5 series, is that the UVD2 HWA decoder can actually handle MVC but would require an updated video BIOS to support the feature in hardware (something that probably won't happen).
While I'd love to have full support for my 5550, it's hard to be upset about a "found money" feature - of course now we'll have a good reason to bug AMD about getting some 6xxx GPUs in for review