http://www.irs.gov/irs/article/0,,id=177937,00.html

The IRS offers its online Economic Stimulus Payments Information Center here.  Detailed and up-to-date information is included, including a long list of Frequently Asked Questions.  There is also information on how people who may not normally file tax returns, such as some Social Security and veterans receiving benefits, as well as some railroad retirement recipients and low wage workers, can still receive their economic stimulus payment.