iCloud: How long are photos stored? I heard that photos stored in iCloud are automatically erased one month after the upload date.

Can someone please explain the retention period for photos, songs and other information to iCloud?

Thanks.
Photos stored in iClouds photo stream are only stored for up to 30 days and up to 1000 photos (whichever you reach first). You should save any photos you want to keep to your photo roll or iPhoto within the 30 days allocated. 

For this and more information about iCloud check out the iCloud FAQ