Same here... I've got an iPhone 4s, Ipad2, just upgraded to the new iPhoto with Lion OSX and even though my iCloud 5gb storage is showing as almost full from the photos applicatoin on my iPhone no photos have ever appeared in my photostream folder on any device. All syncing etc is turned on but just doesn't want to know.
**** update, problem was due to moving over from Mobileme to iCloud; iCloud uses my apple id which I find the most useful as it has all my main details and for some reason my mobile me account is another user name which they haven't allowed me to transfer (or the 20gb free storage o_0) to my apple id. Wiped my old mobile me account and set everything up to the apple id.
I was experimenting with the phone last night, and I noticed that my photostream doesn't work upstairs in my house over wifi, but it does downstairs. So I did a speed test and compared the wifi speed of the iPhone 4S to the iPhone 4, and the iPhone 4S's speed is significantly worse than the 4's. I imagine this is affecting the backup to iCloud speed as well. I can get my phone to backup downstairs, but not upstairs at night when it should automatically.
I read somewhere that this wifi speed decrease has to do with a similar bug that is causing the battery problems on the 4S. The iOS 5.0.1 release should correct this.