I have the Epson iPrint app, but it doesn't work within the gmail app. It's pretty weird: I'm logged into the gmail app, looking at the email I want to print, and when I use iPrint, what comes up on the screen to print is the gmail logon screen, and not the open email I'm looking at.
I decided to try using gmail through the Chrome browser (instead of the gmail app) -- and it worked -- I was able to print the open email -- but it only worked once. The next time I tried it, all I got once again was the gmail logon screen. Very weird. Same thing happened trying to print out a MS hotmail/outlook email through the Chrome browser: all I got in the print window was the mail logon screen.
I don't need to print emails that often, so I'm not about to invest in the $10 or $15 printer apps, but it sure would be nice to print a page now and then.