I recently received several "senior investment" seminar invitations with one of their topics covering the ability to withdraw up to $70K from my IRA each year with no tax.

Does the IRS have a regulation allowing this? If so, what are the details?

Any withdrawal from IRA is taxable income (except your after tax money investment). Early withdrawal is also subject to 10% penalty unless it meets the exceptions.
Read Your U.S. Tax Return: Traditional IRA and Roth IRA (http://taxipay.blogspot.com/2008/05/traditional-ira-and-roth-ira.html)

Qualified withdrawals from Roth IRAs are tax free. He may be talking about how to convert your existing traditional IRA or 401(k) to a Roth IRA. People with incomes > $100K have been precluded from doing this, but in 2010 that restriction will go away. Of course, as part of that conversion you have to pay the income taxes owed now, but after that the Roth IRA grow tax-free.