I've added a Google Site Flavored Search to my blog. so I can play with this and figure out if it is valuable for the narrow range of topics typically covered here. Its located in the sidebar so you'll need to go the site if you are reading this through syndication.
What it is supposed to do is tailor your searches to categories that are related to my blog but the choices for categories that were available when I set it up were a little broad.
Its an interesting service though. Another first for Google.