There is a very interested thread over the Raspberry Pi forums started by user veryevil where he explains how he built a Raspberry Pi laptop based on Motorola Lapdock (normally used with Motorola Atrix smartphone).
This is actually a real hack, because the Raspberry Pi still have to sit outside and you need to make custom cables. But the result still looks great, and veryevil claims the system runs Linux smoothly with a resolution of 1366×768 and the battery can last for hours.
Some other users have joined the party, and improved on the design with shorter cables.
You can check that forum post for detailed pictures of each cables.
Motorola Lapdock used to be an expensive piece of equipment, but Raspberry Pi users indicated it’s currently discounted to 69.98 GBP on Amazon UK and I found it for 81 USD on Amazon US (AT&T Version) which makes it somewhat affordable. You can probably find it cheaper, especially if you are willing to buy a second hand lapdock.