What happened to the 512 bus?

Exactly. Besides, they want to recycle the old gpu with faster bus later and sell it as new.  

I believe it came down to cost to manufacture vs performance increase. Cost won out for now.

This also gives some explanation as to why the old 8800 GTX is still running so fast compared to the new Nvidia cards, and why the HD2900 is holding pretty good compared to the 3870. As inglburt, said, cost is part of it, but heat is part of it as well. Better heat sinks and fans need to be developed to get rid of that heat.

There may be some changes on the horizon, as ATI readies its 4xxx series of cards and Nvidia readies its next lines, but for now, we're not a lot better off than we were a year ago in terms of raw performance.

But again you couldnt get a 8800GTX for Sub ~200 could you?

The reason being here is that 512-bit bus was not needed on the HD2000 and HD3000 series, giving why the HD 3870 performs so close to the HD 2900XT, even though it has less memory bandwidth and should theoretically take a performance hit from it. The 512-bit bus may make a come back for the next generation when more bandwidth will be needed.

Well how much memory bandwidth is really needed for todays newest games say unreal tournment 3 or crysis?

Very true. There is no free lunch in video cards. We can get performance, but we have to be willing to pay for it.

@Graveinmind- The HD 3870 does perform roughly the same as the older 2900, which I tried to indicate but perhaps wasn't clear about. You're correct, the 512 bit bus may come back in the next generation of cards. We just have to wait and find out. For now, at least theoretically, the OP is correct that a 512 bit bus should allow more memory and thus allow more performance.

Where the heck can you get an 8800GTX for under $200US??

Im being sarcastic, you cant hispeed120... the point of the fact being that thought the 8800GT only has 256-512mb it performs close, better, or on par with the 8800GTX whilst costing today, around $180

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Ahh, sorry didn't pick up on the sarcasm. I do agree that the GT and GTS (G92) are pretty insane cards for the price. 8800GTX does have a higher bandwidth, and more flops when overclocked though. Even still, I'll most likely be picking up a GTS when nVidia finally releases the MCP7A.

I Figure that the 512 bit is very expensive. I would hate to think how much money AMD lost due to the HD 2000 series. That card had monster specs but it couldn't touch the GTX.