it'd be nice to have a search box that shows all the wp.com blogs under the keyword searched. it would be a great complement to the wordpress tag system and the tag surfer. i know it possible to do such a search in normal search engines but as we know search engines take a long time to enter newly set up blogs in their directory or system, and a long time to clear out the incorrect or invalid urls. if i search through the tags, it would take forever and not guarantee i can find what i want.
since we have a search box for wp.com forums, a wp.com search box would be a nice addition, i think!