According to Official Google Blog post;
Official Google Blog: Google Desktop now available for LinuxNot only can you rediscover important documents that have been idling on your hard drive for years, but you can also search through emails saved in Gmail or other applications. All office files, including documents and slides created with OpenOffice.org can be easily found. Since some Linux users are program developers, Google Desktop was designed with the ability to search source code and information contained in .pdf, .ps, .man and .info documents. It also features the Quick Search Box ,which you can call up by pressing the Ctrl key twice. Type a few letters or words into the search box and your top results pop up instantly. Keeping with a global focus, you can use it in English, French, Italian, German, Spanish, Portuguese, Dutch, Chinese, Japanese, and Korean --and it works with many versions of Linux too.
So if it is what you like, you can get Google Desktop for Linux at GDL site.