Category filter on Search results

Hi,
I’m currently using Raena’s search hack
http://blog.raena.net/entries/2004/08/06/wphack/
however, because it only re-uses WP’s code, it shouldn’t make a difference….
I think it would be a GREAT idea to have the option to have a category filter on the search results… check this out for example (although my site is still in development)
http://www.noranja.com/search/
The drop menu (when searched) accurately adds the category filter query to the URL, but yet the search results page does NOT want to filter it.
Try a search for “Nike” under any category, and even though I only have test posts in the “Shoes” category, any other category shows it as well in the search results.
Example of “Shoes” results in “Jewelry”:
http://www.noranja.com/search/?s=nike&cat=5