I've updated the site changing the rollover effect to a sliding, scaling highlight that should appear much smoother. I moved the event handler from the underlying silverlight object up to the html div avoiding the windowless plugin differences.
I've also updated the hover shapes on the starting image to match the screenshots below. I changed from a solid brush to a gradient brush as well. It doesn't look so much like a tracing sheet of paper on top of the image now.
Tooltips are the list for next steps, but I need to run off and enjoy some Sunday-ness now
EDIT: If you've already viewed the site, you'll need to refresh the files to see the changes.