I would love to be able to mirror the display of my iPad on a projector for use in a presentation. Is there any software available to do this - on the AppStore or if necessary for use with a jailbroken iPad?
There's no official way to achieve this.
You have to jailbreak your iPad and use a software like DisplayOut (works on all iDevices) to do this.
Just for clarification:
With the iPad2, every app is mirrored on the VGA adapter by default, without any additional measures.
As Studer mentioned, there is no official way to do so. you can use the DisplayOut software for Jailbroken iPads.
If you're more developer oriented, there is also this option