the new revision of the fermi chip that nvidia is working on, to get better yields. but not sure if it will be out that soon to be available in June.
No. That revision is the GF11x line, with GF119 being the first member we know about. That can't come earlier than Q3 since it has yet to tape out and it's at least 6 months from tapeout to product.
GF104 is a Fermi derivative, with fewer shaders. Since it's June, it won't have time to fix Fermi's flaws. Since a Fermi is worse value than Cypress, then a half-Fermi (256 shaders, say) wouldn't compare well to a Juniper. But it should at least be manufacturable due to the smaller die size.