Google has quietly added a new function to YouTube: in the upload section it is now possible not only to to upload or record a video but also to start a hangout and to create an animated slideshow.
You can upload photos from your hard drive or import them from a picasa/Google+ album. Then you can rearrange the photos and choose which effects (transitions) you would like choose. You can also choose from 150,000+ royalty free songs. When done a pan and zoom animated slideshow (aka Ken Burns effect) is created automatically.
Compared to similar services such as Animoto YouTube slideshows have a number of advantages as well as disadvantages:
length | resolution | music | effects | captions | |
YouTube | 15+ minutes | 1080p | 150,000+ -upload | a few | none (only via subtitle file) |
animoto (free) | 30 seconds | 360p | a few dozens +upload | wide variety of styles | yes |
Here is a pre-christmassy example: