A rumor originating at hardOCP states that NVIDIA gave XFX the axe. One of the reasons is NVIDIA's entry into the retail market.
"NVIDIA had intended to move into direct retail in January of 2010, but that did not happen for reasons we are not aware of. Now that NVIDIA has moved into direct retail sales, I was told today that XFX is no longer an approved NVIDIA partner. "
Of course one also needs to keep in mind that XFX made a (and took a risk) choice selling AMD/ATI graphics cards last year. It's just a rumor of course, but it would not surprize us at all.