In our 2011 release the WebAii Tests are called Web Tests and the file extension for Test Studio files changed from .aii to .tstest, but they are the same thing. We have deemphasized the "WebAii" terminology as it implies only Web testing. We now include WPF testing as well.
The "Web Test" and the "Wpf Test" are located in the "Add New Test" templates, designated with check icons(see screenshot).
the Telerik team