Sorry about the confusing title but it is accurate, if you read the post that follows.
Question: What is a portable / ultra-portable system ?
Answer: A computer you can take with you with minimum of fuss and ergonomically minimal footprint.
Question: Why would anyone (in real life) want such a system ?
Answer: Making presentations, working on stuff while on the move, and having minimal time spent on getting back to productivity (like leaving the system in a state that you can immediately resume working in).
Question: What is then the most important (and dare one say - non-negotiable) feature of such a system, given most people's (actual working) reason for buying a netbook ?
Answer: The ability to hibernate.
Not sleep, blinky-blink-I-am-asleep-but-not-really that you cannot put into a traveling bag, or go through an airport with. But honest to goodness I-have-written-all-my-contents-to-disk and I-am-fully-powered-off hibernate. Aka Deep Sleep. Aka ACPI suspend-to-disk.
So does Snow Leopard work (I did not say run) on a Dell Mini 10v ?
I am not trying to put down the hard-working and ingenious developers who have made running OSX on netbooks even possible. This comment is directed at all the users here who say inane and incredibly infuriating stuff like "Oh, I can sleep it, and then it is ready to go when I get back to the desk". (or variations on that theme).
Most rational people do not buy netbooks to work at a desk with (I have an iMac for that purpose, thank you very much), folks. They buy them for the high degree of mobility it provides. And mobility is non-existent, functionally, without an ability to hibernate.
So, why not just use my Macbook ? I have to now, I was hoping for something much lighter than that.