On Technet, I found this line in an article talking about Extending Windows Search:
Microsoft Office Outlook 2007 or later has instant search powered by Windows Search and does not require installation of a separate toolbar.
In another article from the Windows 7 (That’s Vista’s replacement) the engineering team talked about the future uses of Windows Search. Windows Search, or Indexer, is open for use by developers. Even the Google Search Bar uses it. By all indications, it is not going away. The idea is to already search your files before you do. That way you get faster response times. The indexer does have some intelligence though. I knows that there are some folders that it does not need to search. It also knows to slow down its activities once the user starts to utilize the PC and to stop all activity if needed. It also only needs to run once. After that, it only indexes changed files.