Printicular is the app that allows folks to print from a variety of sources: from the device, Facebook, Instagram, Flickr, etc. It allows for the pickup of prints from local Walgreens hour service, or they can be delivered to one's door.
And now, Printicular offers the printing of images from Twitter.
Printicular has a couple of specials running currently; it's offering 30% off prints processed via Walgreens pickup (coupon code: MEAM), and free shipping on home delivery orders of $25 or more.
The Printicular app is available for free on the App Store.