I'm surprised no one has made mention of the Master Pages item from the roadmap? Check it:Second, Whidbey will include features that ensure consistency and code reuse across pages within a Web site. The introduction of Master Pages will enable developers to quickly share layout across multiple pages by designing templates that specify the location of controls, menu bars, headers, and footers. Similar to visual inheritance in Windows Forms, Master Pages allow other pages on a Web site to inherit from a Master Page, automatically acquiring its look and feel. When a developer wishes to change the layout of all the pages, they need only make updates to the Master Page.
This is going to be a great addition to every ASP.Net developers arsenal. Couple that with the new theming and skins that will be in Whidbey and I'm drooling over my keyboard.
Note: the original version of Master Pages is here.
Update: As Frans Bouma points out in a comment, the Whidbey package is more likely to include .NET 1.2, not 2.0.