I would like to add my voice to the original poster's confusion about searching in Mail. It seems that Apple has taken many steps backward with search, apparently trying to read my mind about what I might be searching on. In previous releases I could tell Mail quickly what I wanted to search for, but now I play a cat and (literal) mouse game with the search field, where it *might* give me more options on what I'm searching for, or it might not. I've had to remove my search and re-enter it many times before coaxing a full drop-down of search options. This is perhaps the worst search interface I've seen since the original Sherlock created a riches of embarrasment for earlier version of OS X.
In Snow Leopard I taught all of my employees how to effectively and quickly search for information in customer emails in a variety of ways. I'm the beta for Lion in my company, and at this point I have no intention of upgrading any of my employees, mostly for the reason that Mail search will slow down their effectiveness.
As Apple tries to "simplify" their interface for Grandma and Grandpa, it seems like they're taking away powerful features that small business and other savvy users need. It's a real pity, and I'm hoping that Apple will restore the most obvious of search options in Mail, or give the option to do so. (and while they're at it, put back scroll bar arrows!)
