Hi guys,
First post!
I actually received the ASM URF for Summer 2006. So, the application is a ferocious two part, in which the student applicant and the PI each has to fill out a bunch, plus agree to go the ASM General Meeting. I wouldn't do it unless your PI loves you (and is an ASM member).
Overall, it's summer stipend funding + travel expenses and special presentations at the ASM General Meeting. The ASM GM is a huge Microbiology conference, lots of things to do, see about anything to do with microbiology.
They won't give you summer stipend funding if you already have funding (eg. they only want to give you 1x survival money, not like 10x). But, if you have prior nonstipend funding (eg. equipments grant), they will give it to you (I have a couple grants for equipment already). Also, they will do "partial funding," whereas if you have summer stipend from another source, they'll just give you travel money. Travel part is about $1000.
If you want, you should send them an email; the coordinator (Tiff Fonseca) is rather nice
Hope it helps!