It is possible to transfer all files from one iPad to another. You need to have a stable WiFi connection and the iPads need to be setup in the following manner. Both iPads need to be running version 3.8 or newer.
This is a highly experimental feature. It depends on your iPads and Wifi.
1: The source iPad must be set to master mode and share files needs to be turned on. (Settings->Network)
2: The receiving/slave iPad needs to be set to slave mode and set to ask for files if not found. The server address must match the http:// address of the master.
3: Set the receiving/slave to ask for files if not found. Turn this ON. (Settings->Global->Functions)
4: You need to send a transfer file which contains a list of all the files in the master iPad. On the source iPad/master, choose Transfer Files. (Settings->Info & Help)
Then send the transfer file to the receiver/slave.
5: From the receiving/slave iPad, you then start the transfer. Go to settings->Info & Help->Transfer Files and choose Get All Files From iPad Via WiFi.
It will take a while for all of the files to be sent over WiFi if you have a lot of files.