I am getting very excited here looks very interesting and a lot of fun to play with

Hardware needed

HP TouchSmart All-in-One PC : Touchsmart
Price : 9000 from fona see here

Or

Dell latitude XT2
Price details and here  (starts at $2,399)

Or
HP touchsmart tx2 (starts at $800) here

Software needed
Installed Windows® 7
Installed Windows® 7 Drivers
Installed Windows® 7 SDK
Installed Microsoft® Visual Studio® 2005/2008
Installed Microsoft® Office 2007

A great link with the resources needed and a start training for developing Multi touch applications can be found in that link

I know there is emulator provided with the Microsoft surface SDK that can help with development using Visual studio as demonstrated by Scott Hanselman (see around 14:30).

Good to know
In terms of software you need two things: Windows 7 and proper multi-touch driver for your device. Currently I run on Windows 7 Beta 1 (build 7000 for x86), and when I did clean install today most of the drivers are now available through Windows Update. The only driver I had to install manually was for Ralink WLAN adapter. However the TouchSmart version I have doesn’t have TV tuner, so if yours does you might need to install some additional software. Fortunately Kurt Brockett published detailed guide how to setup Windows 7 on HP TouchSmart.

I really hope we can do something good with that technology looks where the future will be.