ATI R520 is due in October and is looking like it will ship with 32 active Pipelines. It will have a very high price tag and will be extremely hard come by as ATI have had to move onto a new process and yield rates are very very poor so expect long delays on this product and it will no doubt be an extreme flagship product. However it will kick the G70's ass but will cost a lot more and will be hard to get hold off.
ATI Crossfire technology is their version of SLi which works by an external cable linking to cards together and at the moment the technology/drivers are nowhere near as stable as NV's SLi so ATI still have a lot of work to do.
nVidia on the other hand have G70 already in production. The GTX model will be shipping with 24 pipelines and we should have the product in ample stock from the best partners such as BFG, Leadtek and XFX in 2-3 weeks.