Apple recently got a patent passed that allowed for a convertible iMac that would turn into a ergonomic touchscreen computer, and a standing all-in-one. For those unfamiliar, check this page:
http://www.engadget.com/2010/10/01/apple-touchscreen-imac-rumor-just-wont-die/

This is just a proof of concept, and I will try to make this out of stuff like wood or aluminum.

For starters, you need a some regular sized Knex, not the mini ones, and some hot glue (optional)

Step 1: Base Construction

Pretty self explanatory.
You will need:
4 right angle connectors
1 red/orange/green rod (longer then the bright orange/silver, shorter then the longest grey/black rods)
2 smallest green rods
2 blue rods
2 half circle connectors

Step 2: Arm Construction

You will need:
6-12 half circle connectors
4-8 white rods
1 red/orange/green rod
2 blue rods

Step 3: Stand Construction

You will need:
1 grey longest rod
3 red/orange/green rods
2 straight connectors
2 half circle connectors
2 sets of the things highlighted on the image
4 white rods
2 purple/grey things that are also highlighted on the image

Use your hot glue to glue the purple things in the middle of the red/orange/green rods

Step 4: Conclusion

Again this is just a proof of concept, and is really not perfect. There is much to be fixed. The base is not heavy enough, so when you convert it, it will move around. With this design, you will need to take the iPad off, and convert it before you put it back on.

Hope you enjoyed, here are some more pics.