Haven't seen anyone else pop up with this yet, but I was able to modify the Google Bookmarklet (which they call the Google Button) and make it search Google Scholar instead.
Here's one for Mozilla / Firefox / Opera: Google Scholar
Here's one for Safari: Google Scholar (thanks to Steve DiDomenico)
And here's one for IE: Google Scholar
Just drag it up to your personal toolbar folder and you should be good to go.
