How long does the IRS keep your tax records?

Per the IRS (talked to them myself today), tax returns and related documents are destroyed after 7 years. After that point, you can obtain a "transcript", or summary of the line items in your return, but not the actual return or any of the attachments (like W2s and the like). If you didn't keep a copy, or you didn't use a professional tax preparer who kept a copy, you're out of luck. Transcripts are free and can generally be obtained fairly quickly.