Plugging into the Net in China
There are lots of wifi hotspots around cities like Beijing. Many are free, particularly in cafes and restaurants. Almost all hotels have an ethernet plug in the room and you can borrow a cable from them to use it either free or at a cost. Check when booking as it is sometimes expensive in high end hotels.
If you want to get internet everywhere you can sign up for 3G, get a card and plug it into your computer via USB. Its not too expensive and you can get a short term prepaid plan. Check in the mobile phone shops for details with your guide to translate, the options are always changing.
Surfing the Web from behind The Great Firewall
The internet in China is censored. This means certain sites and search terms are blocked. For example you can forget about using Facebook, Youtube and most blog hosting sites. When you search for terms deemed uncool you will get an error "The connection was reset". In fact I just got one when I Googled "Great Firewall" to get more info for this page.
If you must do Facebook while in China then you need to sign up for a VPN (virtual private network). At the moment I am using 12vpn.com and it works great. There are dozens of other options, I am not endorsing any, so do a search and see who you prefer. Strangely enough the VPN signup sights are not blocked it China, so you can still do it once you're here.
iPads, iPhones and other Smartphones
You can get a micro 3G card from China Unicom on a short term prepaid plan and use it in an iPhone, iPad or other device. Bring your passport when you sign up. Then you will have a local number. If you need to dial international or have global roaming then you have to lay down a deposit. Ask when purchasing. If you have an iPad its definitely nice to get a card.
If you want us to put a trip to the phone shop in your itinerary let us know!