I got 3.0 last night on my and my wifes iphones. Nothing new really except now when you are on the home page and you scroll left it takes you to a search screen to search your phone for files. Also it places a voice memo icon on the home screen so you can obviously leave yourself voice memo's. Email in landscape is pretty decent but no other real changes from what I could tell.
Hmm, there's a lot more to it. Ability to delete individual text messages, and forward texts.
Call log now shows location
MMS ability when ATT gets their shit together
Email search feature
copy and paste
sending contacts via vcard
send multiple photos in email
landscape keyboard available in Apps
landscape Stocks App
Shared Calendar support. (i'm really interested in this one, need to read more on it)
PC tethering (not offered in the US, btw) BOO!
And that's just the stuff you see. Some really cool things on the developer side:
Ability for accessorie manufacturers to write apps to talk to their accessories. i.e. an FM transmitter that you can adjust settings in the iphone app. Or, creating accessories for the medical field, thermometers with readouts on the phone, blood pressure cuffs, etc. These can talk via the dock or bluetooth
Integration of google maps with Apps
Turn by turn directions with GPS
Push notifications (real time IM clients, rather than IM to text)
and tons more, this is great update for me