I've just ordered a Acer Aspire One netbook from Laptops Direct and the guy asked if I wanted a O2 3g Dongle with it. Id normally say no as Im with Vodafone, but as he claimed it was unlocked I got it..
Just tested it and yes it is unlocked and is working happily.
The only thing I needed to do is download the vodafone mobile connect software, it recognized the modem and worked a charm.. The O2 software wouldnt let me change the 3g options (username/password/APN etc)..
Oh, Im not sure if you can get this deal without getting a netbook but worth asking and certainly worth knowing about