Note on archived topics.
I found a copy of the HP iPrint Photo app for Windows mobile. I'm not familiar with this app, hope it's what you're looking for.
There is no support for HP ePrint for Windows Phone 7 or 7.5 at this time. Unfortunately... The only way to print from device is to attach the "page" or "document" to an email and send it to your remote access email account (email@example.com)
NOW WE 've got almost december 2012 !!! and ..... there is no app for WP7 and new Windows Phone 8 someone in HP love very much Linux or sleep well :) and don't create apps for new system from Microsoft !!!