They are reffered to by many names. Netbook, Mini Notebook, UMPC, whatever you want to call it, these little laptops are becoming all the rage.
Asus was first on the scene with their Eee PC. It was only available with a 7" screen, sporting Linux. Soon there will be a 8.9" version as well as a 10" version, with the option for Windows XP.
MSI has joined the game with their Wind, which will only be available with 10" screen for now in the US.
Acer just recently announced their Aspire One, which look to be healthy competition.
And last but no least, Dell is getting into the game with a Mini Inspiron.
I bought my 17" Vaio several years ago, and at the time had there been mini laptops like these I would definately have thought twice about my decision. Some of them can get over 5 hours of battery life, all while being small enough to fit into a womans purse, or a man's purse, a murse if you will.
They aren't powerhouses, but my Vaio was intended to be a desktop replacement when I purchased it, and some of these laptops half its size are rocking nearly the same processor speed. For portability, and ease of use, I can see alot more people buying these.
Will they take over the world? Well, the Eee PC had quite a bit of success using only Linux, and with the low entry price to these the modding community may also find them to be fun as well.