The way I understand it is $18,500 is the maximum Graduate Stafford before 7/1/07. After this it will be $20,500 ($8,500 sub + $12,000 unsub). The unsub portion goes up by $2,000 to $12,000 from $10,000.
Since we are health professionals, we are entitled to an "additional unsub" up to $26,667. This gives the total annual Stafford limit of $47,167 based on a 12 mo academic year. It's prorated, so a 9 mo program should only receive $20,000 with an annual Stafford limit of $40,500, and so on.
Everything above only applies to Stafford money. Once you hit an aggregate of $189,125 you are cut off. This aggregate limit includes ALL Stafford money you received from undergrad and grad school.
Your annual Stafford amount is then deducted from your cost of attendance minus other aid/programs/loans (HPSL, Perkins, scholarships, etc.) The difference is awarded in GradPlus or private loans. If you have outstanding Stafford loans from undergrad, your FAO may reduce your annual Stafford amount to spread it out over the length of your education.
Anyway, I hope this helps.
GradPlus is a good deal at 8.5% interest and 3% origination fee. Wachovia has a program that appears to be good. They claim to credit back the 3% origination fee after 180 days and reduce your interest to 7.9% during school. Of course, do your own research and choose the lender that's best for you.