It's what is currently BBC Choice, the digital/cable channel. It's being repackaged and will change its name this Sunday (or next Sunday, I can't remember) and relaunch as BBC3. You can only get it if you have cable or digital TV.
That seems to imply that you'll get it if you have analogue cable, which I don't think is the case. Otherwise, yes. BBC Choice pretty much ends tonight (Friday), then they're running the preview loop for BBC THREE all night tomorrow and the channel starts properly on Sunday.
Annoying think is people with out digi TV still have to pay for the channel through their TV license. Theres a big thing on BBC News today about all the other channels (Sky1, MTV...) saying that it better be good and not waste the license money and not take their viewers away. Shame we cant block BBC channels and save ourselves the 100 quid for the license as i happily do away with them!