Dell's naming system is confusing, so it would be easy to see the "Mini 10" and think that it is available, but the "10v" has a chipset that works with Mac OS X; the regular Mini 10 does not.
Coincidentally, last night I setup my first Dell Mini 10v running Mac OS X. I had my Snow Leopard DVD, the free Netbook Installer application, the instructions from Gizmodo, and an 8GB USB thumb drive; setting this up could not have been any easier. The results are pretty cool, if you are willing to accept the obvious tradeoffs inherent in a netbook.
Today I even ran Software Update, and have the beast running 10.6.3 without a hitch.
As of this writing, there are still a few refurbished models available at Dell's outlet. Although the Mini 10v has been a hackintosher's dream machine, I have no doubt that other computers will come along which prove equally as hackintoshable (I realize that these are made-up words).
Update: A Dell spokesperson tells TUAW that the product was naturally end-of-lifed. Intel launched its Pine Trail Atom processor last year; Dell will be refreshing the mini line with that updated processor. The spokesperson could not clarify the degree to which updated units would be Hackintoshable.