Google recently released Cloud Print, a web feature that allowed you to print documents on your home printer from anywhere. Today, they're going to start rolling out that feature for mobile Gmail.
Now, if you read an email on-the-go that you want to print at home, you can just head to Gmail's mobile web interface and hit the print button from the top right-hand drop-down menu. When you come home, your email will be waiting for you at the printer. You can also print email attachments like .doc and .pdf files. To set up Google Cloud Print, just head to Chrome's preferences > Under the Hood > Sign in to Google Cloud Print and follow the steps it gives you to set up your printer. Note that as of right now, it only works on Windows, and you'll need the latest beta version of Google Chrome to set it up.