Google Desktop is a desktop search application that gives you easy access to information on your computer and from the web. The desktop searching tool will be available as a beta for Mac OS X users since April, the 3rd.

The Mac version only includes the desktop search features, no toolbar or gadgets yet, and indexes file types like:
    - Gmail
    - text files (.txt)
    - PDF
    - HTML
    - email from Apple Mail and Microsoft Entourage
    - iChat transcripts
    - Microsoft Word, Excel, and PowerPoint
    - music and video files, including artist and song names
    - Address Book contacts
    - system preference panes
    - file and folder names.
Google Desktop also searches file types that have a Spotlight importer.

Google Desktop's killer feature is integration with Google's other offerings, specifically Gmail and Google search. Google Desktop creates cached copies (snapshots) of your files and other items each time you view them, and stores these copies on your Mac's hard drive. As a result, you can often use Desktop to find previous versions of your files or ones you've accidentally deleted. Google Desktop also allows users to index their Gmail from Google's servers as well as the contents of their web search history, so that a copy is always accessible to them, even when the computer is no longer connected to the Internet.

We can assume that the rest of the Google apps like Picasa, Gtalk, will be soon available on the Mac too. Google Desktop for the Mac is a Universal application, requires OS X 10.4 or later, is free and it can be downloaded from here.