Though we were hinted about Greasemonkey supporting chrome, an official statement from Aaron (Creator of Greasemonkey script) about the Greasemonkey script on Google chrome was finally raised few days ago. A preview on the future Greasmonkey enabled Chrome, in the form of Chromium limited userscript, will be available for download very soon.
You can still download the Chromium Greasemonkey limited version from the link given above. After downloading the mini-installer or other setup file, finish the installation by appending this line –enable-greasemonkey to Chromium which can be done by right clicking on the shortcut icon –> Properties –> Target field.
Update September 12th, 2012: A new and popular extension called Tampermonkey is available on Chrome’s web store. You may want to download Tampermoneky on Chrome to add news scripts, edit them and manager all your userscripts stored on your Chrome browser.