Siri is improved - International support, including Canada, so hopefully other new things like Open Table/Yelp integration, finding movie times and auto integration (hands free directions) work for us here.
Siri can now launch apps, which is nice.
Siri comes to the iPad
Facebook integration for easy sharing of your photos of your cat.
New phone app with finer control over Do Not Disturb options, reply to a phone call you can't take with a message, geofence an area to remind you to call someone when you leave or arrive.
FaceTime is enabled over cellular data, not limited to wifi anymore.
You can unify your phone number and Apple ID. So if someone calls your iPhone, you can answer that call on your iPad or even Mac. Same thing with iMessage
Improved PhotoStream that allows you to choose people to share them with
Passbook.app to store all your passes (i.e. boarding pass, Starbucks cards, parking pass, etc.)
Guided Access for children with autism.
Single app mode locks an iPad to one app so students can't switch to Safari to look up answers on a quiz. Or, as @jessejanderson reminded me - letting your toddler play with an iPad and have access to just one app.
Maps is the big feature that they saved for near the end. Turn by turn navigation support, uses anonymous real-time crowd-sourced data for traffic flows it can alert you to a different route that might be quicker. You can ask Siri "Are we there yet?" Beautiful 3D flyovers.
No Apple TV that will change the world but given all that they announced, the only people who should be disappointed are the dumb pundits and rumour mongers who worked everyone into a frenzy saying it was coming.
Same with a new iPhone. That's on a yearly cycle now in the fall.
The MacBook Pros with retina display are going to be huge. Just like seeing a retina enabled iPhone or iPad, once you use one your current MacBook will look old and busted. So my advice stands as it did for the new iPad - just don't look at one and you'll be fine.