1. On a touchscreen computer, go to http://www.google.com/
2. Touch the text field to focus it
No Input Panel icon appears. The Input Panel icon should appear next to the focused text field
Note that in step 2, you need to focus the text field by touching the touchscreen, not by using the mouse.
<http://msdn.microsoft.com/en-us/library/ms811573.aspx> has info about how to implement this.
This affects Vista, as well.
Apparently the control over the position of the Tablet Input Panel can be even more fine-grained. See <http://www.code-magazine.com/Article.aspx?quickid=0704142>.