In GAT, you specify the command bar that you want a command to appear, in the following manner:
<CommandBar Name="Project" />
In Whidbey, web projects no longer use the C#/VB project systems.
Because of that, if you want to add a command to the bar you have to use the following GUID for a webproject:
<CommandBar ID="1136" Guid="d309f791-903f-11d0-9efc-00a0c911004f"/>
Pablo