Just went to Beijing last month, it's very Westernized and you will be able to find cash machines. Check out Silk Street, it's by the western embassies, great deals on clothes and shoes. Cab Drivers seem to know little English, so bring a map (hotels should provide)and show them where you want to go. Pollution is very bad there, they burn coal in their homes and cars have no pollution control. Strongly recommend walking around to really get the feel of Beijing.
"Any man who is under 30, and is not a liberal, has not heart; and any man who is over 30, and is not a conservative, has no brains." (Winston Churchill)
There is a surprising rate of illiteracy there, so be prepared to tell your driver where you want to go. I would highly recommend learning some Chinese phrases, such as "How much is this?" and how to say numbers. Holding up fingers won't work because they have different gestures for numbers.
ATMs are quite prevalent in the major cities. These days, virtually all of them accept ATM cards from American banks. China is still a fairly cash-oriented economy, so you'll need cash in more situations than in the US.
Be sure to get a card from your hotel that lists the name and address of your hotel in English and Chinese. It's very helpful for getting back to your hotel via taxi. Also, many hotels have cards for their guests that list major sites in town in English and Chinese. These are often helpful for using taxis in getting around town.
Speaking of taxis, I've always had good experiences with licensed taxis, but some friends have really been taken to the cleaners by freelancers with nice cars offering taxi rides. The nicer cars seem safer and more like home, but I've done just fine with the ones that charge you $0.15 as their base charge and then cost you $2.00 to get from one side of town to the other.
I've had good and back luck with using maps with taxi drivers. Some drivers like maps and others can't seem to read maps at all. Another approach is to try to say the name of the place you want to go to -- I've gotten some fun, impromptu lessons in speaking Chinese that way.
The pollution in Beijing seems to be getting better as they try to clean things up for the 2008 Olympics, but I often get a sore throat from all the pollution. I bring throat lozenges just in case.
If you're into Peking Duck, a pretty good place is the Qianmen Quanjude Roast Duck Restaurant in Beijing. It's quite large and somewhat touristy, but pretty good. It's a little bit south of Tiananmen Square.
Thank you all, looking forward to Silk Street, Duck and answering the cab question. Nice knowing that ATM's are easy to find.
My wife is now trying to find the finest tea shop in Beijing and shoehorn a side trip to the Three Gorges in. I really wish I had seen it before it turned, probably time to get that trip to Havana in before that's too late.