Don't get too excited there ... the news last night reported that the first 53,000 letters to go out listed incorrect amounts
On top of that, the general public is under the impression that this is an added refund when in fact, it's a refund advance for 2001 (go to www.irs.gov for more info) that you'll have to claim on your taxes in 2001.
But if your letter was correct and you get $300, the beer's on you
If you filed single last year, and your income was a decent level, then $300 is correct. This is actually meant to cover the incorrect tax tables used for payroll deductions in 2000, since the tax break is grandfathered.
Y'know, getting a tax refund isn't all that great. It means that you made the gov't an intrest free loan of your money over the past year. I'd rather collect the interest from my savings and pay out at the end of the year. It might only be a few bucks, but it's my few bucks.