caffeinated, read the footnotes of the press release, its explicit in its support:
1. All ATI Radeon HD 2000 products feature AMD’s second-generation Unified Shader Architecture (USA). All ATI Mobility Radeon HD 2000 products feature AMD’s second-generation Unified Shader Architecture, except the ATI Mobility Radeon HD 2300. The ATI Radeon HD 2900 XT features a 512 MB memory bus designed for full performance high dynamic range (HDR) rendering. The ATI Radeon HD 2600 series, ATI Radeon HD 2400 series, and all ATI Mobility Radeon HD 2000 series products include AMD’s new Unified Video Decoder (UVD) technology for high-fidelity HD multimedia playback.
As for Avivo HD - UVD is a part of that technology set, but its not a definining feature of it.