RPG Vault has kicked up two separate installments (here and here) of their E3 2007 report, both of which feature mini-previews for a variety of RPGs and MMORPGs. A bit about Mask of the Betrayer:
Obsidian's expansion pack looks like it will provide everything we can reasonably expect from an add-on. The new single-player adventure should run 20 to 30 hours, and while details weren't forthcoming, it will reportedly wrap up the story from the base game. There will be plenty of new content such as the half-elemental Genasi race, additional base and prestige classes, more companions, monsters, items, etc. Slated to ship this fall, it gives every indication of providing a top-quality RPG experience. I'm awaiting it keenly already.