PVR-350 hardware decoding support in MythTV has ended, at least for the time being. The hardware encoding is still supported.
The developers have indicated that because nobody has stepped up to support the PVR-350 decoding functionality, the support has not been included in MythTV 0.20.
Daniel Kristjansson on the MythTV Mailing list has clarified this. He says "It's no longer maintained but it is still in the SVN head. It will probably be removed shortly after it completely stops working; whenever that happens."
As a PVR-350 owner, what does this mean to you? The encoding portion of this card is still supported, which basically means the card now acts like a PVR-150 or PVR-250.
If you are considering getting a PVR-350 for use with MythTV, maybe you should reconsider. A good alternative would be to get a PVR-150 along with a NVIDIA graphics card. The NVIDIA cards still have supported hardware decoding (XvMC), and can be found for about $50.
At some point, if someone picks up the development of the PVR-350 decoder, the support for it may return to MythTV.