Desktop Radeons with 40nm graphics processors certainly seem to be on the way. A listing for an unannounced Radeon HD 4750 has appeared on a German price search engine mentioning a 40nm RV740 graphics processor alongside other specifications.
Reportedly, the Radeon HD 4750 features a 650MHz GPU with 640 stream processors. The card is outfitted with 512MB of GDDR5 memory clocked at 800MHz (for an effective 3200MT/s transfer rate), and it has a 128-bit memory interface. If my math is right, that means the card should have peak theoretical memory bandwidth of 51.2GB/s—not far below the 57.6GB/s of the Radeon HD 4830.
Schottenland.de shows just one e-tailer offering the card. Said e-tailer charges €129.90 and quotes a 10-15 day lead time. 130 euros works out to around $175 in greenbacks, but the same listing would probably say $130 if it were on the other side of the Atlantic. In fact, considering that the specs look roughly equivalent to—or perhaps slightly better than—those of the 4830, you can probably expect a launch price closer to the $100 mark. (Thanks to Fudzilla for the heads-up.)