There is no way I would use my Lenovo S10 for "real work", however it is a great machine to take on vacation with me, the size and weight are just about perfect for travel and "light use".
It's my belief that ultra-portables will continue to grow in power and reduce in weight and cost until they push the netbooks out of the market, but until that happens, I'm happy with having my netbook for personal travel and my laptop for real work...