Microsoft has released a beta of Windows Desktop Search 3.0 intended for use by those in Office 2007. This version is just a preview of the engine and doesn't include the desktop search application. 

Searching is now integrated into the Office 2007 search tools - no more additional toolbar. It is very fast even compared to the much-improved Outlook 2007 search. The search are updated in real-time as you type, but without the flicker of the built-in search.

If you are using the Office 2007 beta, I encourage you to check out this beta.