AirPrint, Mail and Safari have all been improved through iOS 4.2 (beta at least).
Mail has gained the unified mailbox and threaded view features found in iOS 4.0 for iPhone and iPod touch. It has also gained a print feature, which Apple now refers to as “AirPrint,” though the word Print is used within iOS 4.2 for the time being.
GameCenter for iPad is very similar to iPhone...
There are lots and lots of subtle changes here...
Safari got the print feature, along with an updated icon that lets you know how many Safari pages are open at once.
Events have been added as another option for Picture Frame. The ability to disable 3G in favor of EDGE, reducing battery drain and data speeds. A proper location services menu now provides iOS 4-standard control over notifications and permissions for the location hardware in iPads. Enlarged text has been added to the accessibility settings to make the iPad’s screen easier to read. A variety new keyboards have been added. The new spellchecker has been added to the iPad.
Parental restrictions have been expanded to add controls over deleting applications and changes to e-mail accounts, as well as disabling multiplayer games over Game Center. calendar display options to use either the Buddhist or Japanese (imperial) date systems have been added to the prior Gregorian calendar as options, as well.