If you're a dirty, dirty iPhone Jailbreaker or iPhone Unlocker, move right along because I'm sure it's going to take awhile for this to shake out. If you're a mere mortal, though, go on and open up iTunes and apply the update to version 1.1.4. What's on it? "Bug fixes." That's all we know for sure just now.
Hopefully one of the bug fixes is getting rid of the dropped calls (especially with Bluetooth) that folks have been reporting (hat tip to Merlyn3D for reminding me that this issue persists).
Hopefully it also contains some behind-the-scenes updates to get every little thing ready for the SDK. Good thing this year is a leap year - it gives Apple one more day to get that SDK out. Or maybe it really will be late. I guess we'll know for sure before the week is out.
Thanks for the heads-up, Chadman!
Update: Installed and I'm still impressed with iTunes' backup and restoration ability - everything was exactly as I left it, from the pin I was looking at on Google Maps to Web Clip icons on my homescreen. Poking around, it sure doesn't look like there are any new features. Chadman mentions that it's a full 162.1mb download, that sounds like a "bug fix and framework for the SDK" to me...