While there is a Google Search application for Windows Phone, it is definitely not something which will shake your world. However, according to recent reports, Google Search now not only recognizes your Windows Phone but also offers to put a Tile on your Start Screen for easy access.
The good folks at WPCentral already received this and, as you can see in their screenshots above, going to Google on your Windows Phone should display an option to pin the page to your Start Screen. If you choose to do so, you're taken to a special page, formatted perfectly for the WVGA experience on Windows Phone, from where you can pin the site to your Start, resulting in a Tile for easy access.
Note: The feature is probably being rolled out in stages so chances are you'll likely have to wait until it reaches your region, if not yet available.