http://www.irs.gov/individuals/article/0,,id=96199,00.html
If you receive a letter or notice from the IRS, this website will explain the reason for the correspondence and provide detailed instructions of what to do. It provides helpful forms and publications you may want to review, frequently asked questions, and tips for next year.
The IRS is redesigning and revising its correspondence for clarity, effectiveness, and efficiency. The new format includes a plain language explanation of the nature of the correspondence, clearly stating actions the taxpayer must take and the letters must present a clear, clean design.