pelihu
I'm pretty sure the plus loans are for parents, so if you're parents are borrowing money to pay for your education, that is available to them.
I believe Graduate PLUS may now be taken out by students enrolled in an approved graduate program. The PLUS program, originally meant for parents, has now been amended to allow "creditworthy" students to also borrow money under its auspices. The interest rates on PLUS loans are fixed at 8.5%, the Stafford loans at 6.8% are therefore a better deal. However, I believe a student may only borrow up to $20,500 per year under the Stafford program, so it's likely a lot of us would need to dip into PLUS or private loans if we're looking to borrow more than $41,000 for an MBA. Some lenders, IIRC, do give incentives of up to 1.75% on PLUS loans, but the origination and guarantee fees can be pretty hefty at ~4%. Furthermore, if the credit crisis continues for much longer, we could expect these incentives to go the way of the dodo.
With Prime/LIBOR at substantially low levels, it makes sense for students who anticipate paying off the bulk their loans within 2-3 years of graduating, to actually consider private loans as opposed to the federal ones discussed above. However, how good a deal private loans end up being depends a lot on your credit history
For an example of a website that compares incentives offered by lenders, by loan type, see:
https://gmatclub.com/forum/p489529#p489529