Wow, this is big news. No drivers yet, but the Linux Drivers Project have their name on it, and I trust those guys.
A while back I wrote about adding extra displays via a USB video adapter, on my old laptop. Long story short - it's hard as nails, and the results were fairly crappy, and it's not possible any more anyway with most laptops since the move to RandR 1.2-based drivers for intel, radeon and nouveau.
If you need more monitors and your graphics cards are all maxed out, DisplayLink really is the best option these days. You can get a USB video adapter based on DisplayLink, or just monitors with DisplayLink baked in which plug straight into a USB port. DisplayLink does a lot of special-sauce compression to get pretty decent performance for most operations over the USB link. It's a good technology. But, for a long time, it's had no Linux drivers, so you just couldn't use DisplayLink hardware on Linux at all. Once this project bears some fruit, it'll be really nice for people who want a couple of external monitors connected to a laptop (or netbook!), or the other various use cases for this. Nice to see it at last.