Trying it out
Now for the fun part. Google gives you the option to print a test page from your desktop, but in my tests this didn't work. However, printing from my mobile device did. So instead of trying the desktop version, open up your Gmail account using Google's Gmail Web app on an iOS or Android device. Also, make sure your handset's Wi-Fi option is turned off and that you are sending the print request over 3G. This step isn't necessary, but using 3G instead of Wi-Fi will verify that Cloud Print works when you are not on your home or office network. Now, just open a message to test your Cloud Print settings.
You have two choices when you print something using Cloud Print: you can either print the e-mail message or you can print the attachment. In my tests, there wasn't an option to print both at the same time.
Printing a message
In my tests using an iOS device, you will see two downward facing arrows next to the trash icon at the top of the message screen. This opens a dropdown menu that should show you an option to print. Google says it is rolling this option out over the next few days so you may not see it right away.
Clicking on Print will open up a second browser window that will show you all the possible printers you have to choose from on your home or office network. Just select the printer you want to send your print job to. Once you've done that you will also have the chance to set a limited number of options for your print job such as color or grayscale, portrait or landscape and the number of copies you want to print.
After you have your options set, click print at the bottom of the screen. You will get an alert telling you that Google is creating a new print job. After it's finished the alert will change to "Print job added." A few seconds later, a print job should start from your designated printer.
Printing an attachment
To print an attachment, just select the "Print" link next to your attachment's file name in Gmail. Then follow the same process as above to choose your printer and print your document.
Cloud Print: What you need to know
In my tests, Cloud Print was a painless way to print from anywhere to your Cloud Print-enabled printers. But there are a few things you need to keep in mind. The first thing to note is that you must keep the computer that you installed Cloud Print on running if you want to print. If the computer happens to be powered down or be offline, Google will start the print job the next time that machine comes online.
In my tests, you did not need to be signed in to your Google Account for the print job to work. You only needed to have your computer on and to be signed in to the Windows User Account (not your Google account) you first used to setup Cloud Print.
Mac OS X and Linux machines can't support Cloud Print yet, but you can view your Cloud Print history from any computer by signing in to your Cloud Print-enabled Google Account and visiting Google.com/Cloud Print. Google also plans to allow you to share your networked printers with other Google users, but that feature has not yet been added.
If you need to print documents or e-mail remotely, Google's Cloud Print is well worth checking out.