If you moved to iOS 5 on your iPhone and downloaded the latest version of iPhoto (that allows for Photo Stream using iCloud), you may have noticed that your iPhone is no longer recognized by iPhoto when you physically plug it into a Mac running Lion. iOS 5 brought all sorts of new features, including WiFi sync and automatic download of your phone's new photos over the last 30 days using Photo Stream (part of iCloud). But with that power comes the inevitable hiccups.
These new features and conveniences can create a problem if you had old photos hanging around on your iPhone that hadn't been transferred to iPhoto.
You might think, "Big deal, I'll just use the wang-bang new iCloud to transfer my old photos." Nope. Only new ones. What I did to fix this was to follow some of the information in the troubleshooting link below. The primary fix for me was unplugging and replugging the docking station from my Mac Pro. That seemed to fix it and now my iPhone is recognized by iPhoto, even with Photo Stream and WiFi syncing enabled. Time will tell, but always open up Image Capture to see if your computer is recognizing your iPhone's physical connection (via USB).
Try using the photo-management software built in to your computer's operating system:
Mac OS X: Open Image Capture (located in the Applications folder).[From iOS: Unable to import photos or device not recognized as a camera]