Google Desktop for Mac has been updated adding support for Mac OS X 10.5 Leopard, among many other changes.
In addition to Leopard support, Google Desktop also now allows indexing of drives where Spotlight has been disabled; Desktop no longer tries to index PGP disks; Time Machine won't back up Desktop indexes, nor will Desktop search Time Machine backups; and Desktop preferences pane now supports keyword searching in System Preferences for various settings.
There are also some architecture improvements in the new release. Google removed some Spotlight dependencies; removed the use of Input Managers; and they removed use of files in /System.
Google Desktop is a free download from the company's Web site.