do searches for "R390" and "R420" as well.
R420 might actually refer to something else labelled at the same time, or as generally assumed (IIRC) it might be referring to the same thing. There is a bit of naming confusion due to some plans changing, apparently.
What the names mean, really, is: a new (much) faster part is expected in the fall, we're not sure what it is, and that the R400 design that used to be talked about for that time period was delayed and aimed at a higher target. This is apparently because this new part delivers extremely high performance ("2x R300" seems to be the ballpark) in the interim, the DX spec isn't going to change for a while, and the R350 (9800) already seems able to expose sufficient OpenGL 2.0 functionality.
This is (pretty solid) speculation, and I think anything further (atleast as made by other than the sources of the information, who might have provided more info than I recall) is speculation based on this speculation (i.e., not so solid).
Related search terms to help flesh out speculations (solid or not): "Cadence", "MAXX" (within the past month or two).
