I initially wanted to use a pc with a touch screen keyboard for user input and display out put from the arduino.
With the recent surge in Tablets and Pad's is it to possible to use these to interface with the arduino?
Do they have host USB ports? Then likely yes. Other ways can also be found.
Most have usb ports.
What language do they run on?
For android tablets, look into amarino
http://www.amarino-toolkit.net/
And the android accessory kit from google
I would imagine that interfacing with the iPad would be more difficult because it is so locked down, but you can get an apple connector broken out so you can solder pins to it. There's also an app that works with the Ethernet shield I think, it shows the controls/display the arduino tells it to
Most have usb ports.
Most have USB client ports. The Arduino is a USB client, so needs a host port to connect to. Alternatively, you can put a host shield on an Arduino, and connect that to a client device.
If you have an Android device, bluetooth is a good option.
What language do they run on?
Android development is Java based, mostly. iOS development is Objective C.
If you have a ethernet or wifi shield, then a web interface is also possible.