3xx series cards have been in both oem and latterly laptop models in Dx10.1 from since around October last year. 310, 330/5, 350/360m are particular models I'm aware of. Similarly the 100 series, Apple and other oems have been using them without any store cards purchasable by joe-public. New Apple G5 we received @ work has a GT120 in it, equiv of a 8600GT iirc.
The naming GTX380 was originally speculatively invented on a forum also. Similar to the GTX4xx naming.