Juru, an exprimental IBM development from Haifa written in Java, is a
full text search library written in Java and dedicated to small/mid-size collections where precision is a must. It efficiently applies state-of-the-art search algorithms producing highest-quality search results.
Apparently it’s already inside WebSphere Portal, but an implementation called Tamnun Juru Desktop search puts a browser interface over the search facility, "tamnun" meaning "octopus" in Hebrew. One of the good things about this, apart from its independence from the expensive WebSphrere, is that unlike Google Desktop to date Juru searches Notes.
I’m not sure if it’s commercially available, but if I find out I’ll tell Slaw.