I found information at http://www.irs.gov, but still no indication of whether this is an advance against 2001 taxes, or a straight refund. At
http://www.irs.gov/pub/irs-pdf/n1275.pdf you find the notice that was sent out to those getting refunds. Again, this does not provide any additional information.
At http://www.irs.gov/pub/irs-news/fs-01-09.pdf is a fact sheet which basically rehashes the same info. But they call it an 'advance payment', which leads me to believe that I was correct. I wish they'd just come out and say so. If anyone else can find explicit information stating that the $300/$600 will automatically be subtracted from your refund amount (or tax owed), I would appreciate it...
This document seems to imply that the advance payment should not be claimed as a rate reduction credit, which I didn't (so I filled out my form correctly). If it was indeed an advance refund, I feel like I was misled. I'm wondering exactly what the true tax reduction was (in other words, if I had filed the exact same return last year, how much less money would I get than I did this year, including the $300?).
My brain hurts. I hope someone can say definitively if I got screwed by the IRS or not.