Alt Text has been included as one of 10 weblogs in a study/project in developing an open source search tool called latent semantic indexing (LSI). From what I have seen it is pretty promising. Some of the results may not contain the keywords you entered, but use the LSI algorithm to determine relevancy based on like words and topics.
There are still some holes in it as it is in development. It works with keywords only – there are no phrase searches allowed. Words that appear in only one post are not indexed, and the interface leaves a lot to be desired, but it is a very cool idea that I hope spreads.
My dad on President W’s recent surgery: “They are looking for his head.”