If you filed your federal return electronically, I found a nice little resource over at TaxAct.com that can give you an idea of when your refund should arrive. Basically it looks like they divide filings into weekly cycles that start and end at 11am EST on Thursdays, with direct deposit refunds being sent the following Friday (note: this is the day they initiate the transfer, meaning you’ll probably receive it a couple of business days later) and paper checks being sent a week later. Here a link to the chart:
http://www.taxact.com/products/all_efcycle.asp
You can also access specific information on the status of your return from the IRS website here using your social security number, filing status, and refund amount.