Leading up to the WWDC, Twitter users were excited to learn that iOS 5 will feature system-level integration with the popular social networking service, specifically with regards to its photo sharing functions. At that time, we wondered where Facebook was during all of this, considering that it hosts nearly 100 billion photos, yet had no premier iPhone photo app of its own. Today, we may know a little bit more.

TechCrunch has revealed a slew of images that appear to be part of some kind of photo-sharing app currently under development by Facebook, and they look pretty hot. In the article's embedded pictures, you can see elements like facial tagging, multi-user photo albums, and location-aware photos, all within an iPhone interface.

Now, while it's doubtful that the existence of this potential app is a reaction to the iOS 5/Twitter news, the timing of its revelation most likely is. However, we notice that TechCrunch stops just short of revealing from where they received these images. They never actually say that they were leaked from a Facebook insider, or indeed who their source actually is. Until we get confirmation that these pictures are the real deal, we'll continue to keep a wary eye out. Still, this thing could be a game-changer -- what has you more excited, Twitter iOS 5 integration, or this potential Facebook photo app?