They are making new Viper cards (040/25, 040/40 and 060/60). Like fragment, I'm waiting for the 060 board from Power Computing. I ordered mine at the end of May. Power have now removed them from their site.
They've been giving me the runaround, but now I know that Vesalia aren't shipping theirs I feel a little better about it (I'm still unhappy about it taking so long tho).
I don't think anyone but the makers of the new Vipers would know if they're compatible, and chances are they haven't tried that yet.