A week after the sort-of-official announcement, Microsoft's released screenshots of Perfect Dark on Xbox Live Arcade. It looks lovely.
According to the Xbox.com product listing the XBLA version is in development at 4J Studios, that of Banjo-Kazooie and Banjo-Tooie XBLA fame.
The XBLA update sports 1080p, 60 frames-per-second visuals (with re-done textures and models by the looks of these shots) as well as various Xbox Live options. Fingers crossed for online multiplayer and co-op!
There's also a free Perfect Dark premium theme sitting on Xbox Live Marketplace, if you're interested (which if you're looking at this article, we assume you are).