In a surprise move by ATI it appears that they are still looking to cater for the AGP platform, even with their new DX10 range. According to our source article, there will be an AGP version of the Radeon HD 2600 (RV630) and HD 2400 (RV610) made available, but we probably won't see them until June or a little later.
The good thing is that these cards will support Avivo and all these fancy Video and 3D features and they will work in old motherboards.
Now we just have to wait and see what the opposition are going to bring to the table. Nvidia would have to be crazy to leave the upgrade market exclusively to ATI, but we have heard no mention of AGP support at this point in time.