The OCR feature in SkyDrive, which is powered by Bing, is now being rolled out to users over the next few weeks. It recognizes text which may have been taken in a photo and stores it in the metadata.
This feature, which is rolling out over the coming weeks, allows you to search from the desktop for the content of Camera Roll photos that have had text extracted from them.
For example, you might have taken a photo 6 months ago of the menu of your favorite restaurant, but can’t remember where it’s buried in your Camera Roll and want to remember the dish you had. You can simply type in the restaurant name on your desktop and Bing Smart Search will search text of your Camera Roll photos and pull up the picture of the menu with the restaurant name printed on it. With the power of smart files, this will work even if your Camera Roll is marked for online-only access. The moment you open the photo, it will be instantaneously pulled from the cloud for you to view the full version.
Source: Inside SkyDrive