Google Cloud Print is a free service from Google that lets you print documents on your computer remotely. You can attach any of your printer to Google Cloud Print, and then print documents from some other computer on that computer. You can even print from your mobile device, and send prints to your printer. The best part is that printer does not even needs to be on, and it will pick up the print job when it is turned on. This service is completely free.
Google Cloud Print is a fascinating service from Google. It is available in latest beta version of Google Chrome browser that you can download from here. Once you have installed this, you will see an additional option of Google Cloud Print under Google Chrome options (see screenshots and installation guide here).
Using that, you can connect your printer(s) to Google Cloud Print service. Once you have done that, you can choose print option from any Google app (currently only a few apps are enabled, like Gmail). Going ahead, Google is planning to integrate more apps to use Google Cloud Print functionality.
From these Google apps, just choose print function, and Google will automatically send the print to the printer that you have attached to Google Cloud Print. In case your printer is not connected at that time, Google will send those prints to the printer once the printer is turned on.
Also check out remote printer finder.
Google Cloud Print is quite a nice service, but has to be enabled with all the applications so that it can be used from anywhere. Google Cloud Print is not officially supported on desktop apps rights now, but here is nice tutorial that explains how to use Google Cloud Print from PC.
All in all, Google Cloud Print is a useful service, but has to quickly ramp up, and come out of beta.