At first, it seemed that some partners jumped the gun and prelaunched AMD's Mobility Radeon X2300 (allegedly an RV610 part) but, in the end, it turns out that AMD will mix its present DirectX 9 and future DirectX 10 parts in its X2K lineup.
The X2300 is actually just a rebranded X1300, and the probable reason for the change was a performance delta between 690G with X1250 graphics and the X1300 - X1250 is based on old X300 chip, while X1300 was newer RV510 part. AMD marketeers thought it would be a good idea to separate the high-performing part from the lower ones.
Sadly, AMD looks like continuing with ATI's old naming convention that mixes several generations of graphics chips in a single product family (X1K,X2K series). Not quite what we'd expected from the company's promises that things will be more transparent in the future. ยต