I have the HTC Rezound and it's running Android ICS , I just went into my Gmail and opened a mail , then I went to the bottom edge of the phne where there are four permenent sensor buttons , Home , Settings , Return and Search. While the mail is open I press the settings button and a list of options comes up with print being one of the options. While typing this post I decided to try what I'm suggesting since I have not previously printed from my phone.
I went into my Gmail and selected and opened an email and that may be the key as it has to be open. While the email was open I selected the sttings option and at the bottom of the pop up list was print , so I selected it to print. I was presented with a seies of steps to set up my phone to use the wireless router to connect to the printer I have and it took just 5 min. Then I was able to print the email.