iCloud Backup frequency

Unless I'm missing something under manage, it doesn't actually tell me anything about how often iCloud would make backups of my iPhone and iPad. It only gives an indication of how big said back ups are. All I'm asking is how often does iCloud backup and iPhone? It is on a schedule (meaning, every 24 hours or so) or is it every time it's connected to a power source?

Also, iTunes says that my device has been backed up into iCloud (last backup was at 8:30 pm). However, when I look at Storage and Backup settings under the iCloud menu in my iPhone, it says "Last Backup: never" and there's an option to "Back Up Now". What's the difference between the two (the backup info in iTunes and the backup info in my iPhone)?

Forgive me if I'm not being very clear.

Thanks!

just some additional information...

i also have an ipad. my ipad's back up (1.2 GB) is now complete. iCould settings on the ipad and on the imac in system preferences says so. my iphone though is still incomplete.

This leads me to believe that the first back up process to icloud takes a looooooong time.

Just wanted to update this thread.

In the end, my phone did manage to back itself up into iCloud, albeit after a very long time. Whether you let iCloud do it in the background or force it to do so under iCloud Storage and Backup settings, it will back up. Once it finishes, iTunes and your iDevice should match the latest back up time.