Do you need OS Lion to run iOS5 or just for iCloud?

You don't need Mac OS Lion to install iOS 5 on a device. If you want to use iCloud you need Mac OS Lion though. Just make sure your Mac is running Mac OS Leopard and the latest available iTunes and you can install iOS 5 on any iOS 5 compatible device.

You can set up iCloud, without Lion, you just can't do the syncing from an older Mac. You can access it from iCloud.com.

You can also use it from some Windows computers, with the iCloud software.