Specifically, Brother iPrint&Scan lets you send photos from your device to your printer over your home Wi-Fi network. You can choose an existing photo from your album or snap one on the spot with the camera.
The app also supports full-color and black-and-white scanning from your all-in-one to your iPhone. That's a great way to capture photos and documents for on-the-go viewing. Scanned items can be saved to your photo album, e-mailed in JPEG or PDF format, or opened in other compatible apps (which aren't listed anywhere that I can find--on my iPhone, iBooks and Stanza were my two available destinations.)
iPrint&Scan is a snap to configure and use. It quickly and effortlessly detected my Brother MFC-490CW printer (one of 17 compatible models), and with a few taps I was printing and scanning photos. The app gives you control over basic settings, like paper size, media type, and number of copies.
Best of all, iPrint&Scan is free. If you own a compatible Brother all-in-one, it's a must-have.
And don't overlook more universally compatible print apps like Print Magic, which can handle not only photos, but also Web pages and the Clipboard.
Know of any other worthwhile apps for printing from your iOS device? Name 'em in the comments.