NVIDIA's naming schemes can be confusing to even the most seasoned geek. Rebranding of GPU's like the 8800 GT to create a new 9800 GT often times make it difficult to understand where a GPU's performance will fall into line with the rest of the series. Often times consumers mistakenly buy a card from a new series that is actually lower in terms of overall power to their current card, thinking that the new line should mean a superior product.
Unfortunately it looks like NVIDIA is at it again. The company has decided that the current GeForce 9 series will be taking on a new name and new designation. All 55 nm 9000-series GPUs will carry a new G-series name.
The 8800/9800 GT will now be branded GeForce GTS 240 while the 8800 GTS 512, 9800 GTX/GTX+ will take on the GeForce GTS 250 brand. Details on the naming and numbering of the mainstream cards such as the 9500 GT and 9600 GT are a bit speculative, as are the naming schemes for the value line of 9300 and 9400 GT.
The naming should be easy enough to follow with the cards being rebranded according to the market segment they are intended for. To be more specific, the GTX cards will be high-end/performance solutions, GT goes for mainstream, while G would mean the card is an entry-level. The number designation remains identical with, lower typically meaning slower.