Here's something we've needed - Mary Hodder is taking a look at RSS Search tools and aggregation. This is part one of six that she's doing - sounds like she's going to go into some depth.

In today's post, she explains the apparent (but not actual) discrepancy that Scoble discovered between Technorati and BlogLines - it's all a matter of what they count, and how they count it. Read the whole thing, and you'll know what you're looking at in the various search engines.