I have the same exact problem, as of the latest Q1, 2010 release.
You can see the problem, even in the demo:
Just select Postion: Left, Orientation: Vertical and you will see how they are now flush to the bottom. I have been browsing the source control, and it seems to be an issue with Visual State transformations changing the orientation of the ItemsPanelTemplate:
<RotateTransform Angle="180" />
I think this causes the TabWrapPanel's TabStripPlacement property to inverse. However, even when I try to counteract the process by setting my own TabControl's ItemsPanelTemplate:
<telerikPrimitives:TabWrapPanel TabStripPlacement="Bottom" /> <!-- equivalent to "Top" when inversed? -->
It doesn't seem to work. I presume it is because is because the ItemsPanelTemplate gets overridden somehow when the TabStripPlacement is set to "Left".
Please provide a viable workaround! Thanks.