It's an external graphics card technology, codenamed Lasso. One of the uses of this is to give you the capability to add one or more high-performance graphics cards like the upcoming R600 to your notebook.
They're calling it Lasso and it'll go a bit further than having an external graphics card for a laptop. Lasso will be able to house multiple graphics boards providing what could frankly prove to be hilarious processing capabilities... and those of you keeping up with the GPGPU scene will know that it's not about games performance. Modern GPUs can do some serious general purpose wet-work, leaving the CPU cores to work on other things.
Details right now are scarce, but imagine having a pair of R600s plugged into your laptop, or indeed augmenting a small form factor PC, or a workstation...