I like the idea of this, but it didn't work for me. The widget shows, but when I try to search for a tag that I know exists, it returns no results.
It seems the URL gets corrupted. When I search, for example, for tag1 in the uncategorized category, my URL looks like this:
I played with the URL, and added & before "Array" and it worked.
Is there a way to get this fixed?