Kaldor :
The 8800MGTX isnt even as fast as a desktop 8800 GT, or a 8800 GTS 512, and wont touch a true 8800 GTX. Its about the same as the dog slow in comparison 8800 GTS 640, which is approaching old age. Specs below. The 9800MGTX is probably about on par with the 8800 GT. Nvidia is selling 2 year old tech, for about $500 a pop. Thats because they have the only decent solution out there at this time.
8800M GTX - about $500
Stream Processors - 96
Core Clock (MHz) - 500
Shader Clock (MHz) - 1250
Memory Clock (MHz) - 800
Maximum Memory - 512MB
Memory Interface - 256-bit
Power consumption: <50W
There, fixed for you.
That's why it's relatively expensive and stuff isn't as fast as the desktop parts right now. As I said before, think of it as an 8800GT with some of the SP's disabled, as that's much closer to its true architecture than the 8800 GTS G80. As for 2 year old tech? The 8800GT came out under a year ago, and this is an improvement over the 8800 GT as far as technology is concerned. It uses far less power to achieve only slightly less performance.
Currently, 7200RPM 320GB notebook drives go for $190. This doesn't mean that they're selling "4 year old tech" just because the desktop 320's were available back then. It just means that it's harder to get the same capabilities crammed into the low power, small size notebook environment.
Because of these limitations, desktops will always be faster for the same amount of money. However, that doesn't mean that there aren't good reasons to get a gaming laptop. A gaming laptop is wonderful if you move around a lot, as all you need is the laptop, the power adapter, and a mouse, and you have a good gaming platform on the go. Depending on your situation, that may or may not be worth the extra money, but it certainly isn't something that's caused by nvidia dragging their heels. The G80 was never made mobile because of the massive power requirements, I'd bet similarly for the GT200. The G92 was the first high performance DX10 card they made that had little enough power draw to make a viable mobile.
As for ATI, I look forward to the mobility HD3870. As for mobility 4 series? I have some doubts about how quickly they'll be able to get those available. The current power draw and heat levels are too high to stick in a notebook without significant modification. They'll do it eventually, but they won't come out soon. Notebook GPU's aren't limited due to artificial holds right now though, they are limited because of the much lower power and heat levels that they must conform to in a notebook in order to work at all. An average gaming notebook has 130W or so for the entire system - a monster notebook has 240 or so. This includes the monitor. That is the biggest reason why the notebook graphics and CPU markets lag behind the desktop in performance.