There's been a lot of buzz over the iPhone optimized version of Facebook in the past couple of days, and with good reason--it rocks. It does nearly everything the full version of Facebook can do, sans apps from the Facebook apps platform, which I assume are on their way later this year. Everything is rolled up into a tight little package using a simplistic set of two rows of tabs to cover core navigation, and a sliding interface that mimics the iPhone's signature UI. To get there, just point your iPhone (or browser) to http://iPhone.facebook.com.
Like the full version of Facebook, the iPhone iteration centers around your profile, friends, messages, and the home tab, which contains the Facebook news feed, along with any upcoming events and notifications. You can browse profiles and check out your friend's links (which open up in new Safari windows). The real killer app though is the call option, which will pop up assuming your friend has made their phone number available. This works with e-mail addresses too, but the phone numbers basically turn Facebook into one big mobile phonebook for your friends.
There are a few things missing from the iPhone version of Facebook that I'd like to see added. The first is groups, which are mysteriously absent. Poking is also missing in action, which is unfortunate because poking on the mobile version of Facebook results in setting your friends on fire--a small but very amusing perk. There's also no way to edit your profile without logging into to the regular Web site. Lastly, the included photo galleries are really well done, but don't let you zoom in and out, nor save them to your device.
This app is a great example of what can be done to work around some of the limitations of the iPhone not having an SDK. If this were a bonafide app, things like notifications and an integrated mailbox would make great additions to the iPhone's current lineup of Web services turned apps. In the meantime, if you've got an iPhone and use Facebook, this is definitely worth bookmarking.