MYMUSAIC is a free iPhone app that lets you create a slideshow from your photos and music, using images from your Camera Roll or those submitted by friends.
The result is nothing fancy, using dissolves as transitions exclusively, and the app fades the music when the slides have run out. But it's quick and easy. One nice feature is that the app tries to match transitions to the beat of the music. The app does allow you to change the order of your images. Slideshow movies can be shared via email or text message. The service is also available from a web browser, so you can access your movies from anywhere and on any device.
The only glitch I saw was that a movie I uploaded never showed up in the local or uploaded list. It just seemed to vanish into the electronic ether. A second try worked fine, and user reviews of the app are quite positive. There are plenty of slideshow apps for iOS, but most create them locally and don't have any sharing abilities.
MYMUSAIC is a handy little app for quick creation of a slideshow movie to share with friends. It's not a universal app, so only iPhone or iPod touch users will get full resolution screens. The app requires iOS 4.3 or later, and it's optimized for the iPhone 5.