End of May!? Oh man, I really hope not, but the pessimist in me is growing louder and stronger with each passing minute, hour, day, and week I don't hear from Admissions. Yargh!
Sorry, I meant "rolling admissions". Basically, what you've described - they look at apps. as they come in. Effectively making it first come, first served. One can only hope.
Am thinking of asking U of IL for an extension on my pending decision; just say I want to know all my options before pressing "go". We'll see whether or not they buy it...