NVIDIA hit their stride powerfully when they released the G80 core many years ago, bringing us the 8800GTX that had more power than we knew what to do with (at the time), and also releasing cards such as the 8800GT, 9600GT and other derivatives that we've come to know and (mostly) love.
ATI caught up and in many ways are now in a better position than NVIDIA with their ultra-affordable performance cards in the 4800 series, with their 5800 series coming very shortly with performance that is going to change the entire scene again, supposedly trouncing the best that NVIDIA can currently muster.
NVIDIA have bounced back in the midst of the 5xxx series news to announce that their next series of cards are not going to be based on a redesigned GT200 core, but rather will be based on a completely new core architecture currently codenamed the GT300.
They're claiming that the GT300 has performance significantly higher than anything ATI and their RV870 core can manage, and that if they use two of them in their GX2 arrangement they'll take the top spot again as the fastest graphics card on the planet.
The launch for the GT300 is rumoured for late November, which places it just after the 5xxx series launch. While it's difficult to determine at this stage whether the performance claims are true, or if it's just NVIDIA attempting to take the wind out of ATI's sails, it's going to be interesting to find out who will take top spot - and we'll know for sure by Christmas.