A couple of stories over at TPM tie into each other quite well. Both Ann Coulter and Republican South Dakota State Representative Hal Wick (among others) are arguing that if the health insurance mandate is constitutional, so must be requiring every citizen to own a gun. Wick even went so far as to introduce a bill to the SD legislature requiring everyone to own a gun.
This is an epic fail on their part, especially on Wick's part - the Commerce Clause in the Federal Constitution quite obviously only applies to the Federal government, so whether or not the South Dakota state constitution would permit his bill is entirely irrelevant to whether or not the Federal Constitution permits PPACA.
But there's more levels of fail, even considering solely the Federal issue.
The constitutional argument in favor of the mandate is that the rest of the reforms in PPACA fall within the enumerated power to regulate interstate commerce, and that the mandate is necessary to give effect to those enumerated powers. Neither Hudson nor Vinson properly treated that argument in their rulings against the act.
Coulter and Wick fail to connect forced gun ownership to an enumerated power, and further fail to explain how it's necessary to force gun ownership to give effect to that power. Congress does, however, have the power to provide for the arming of the militia, and one could term a must-buy law an exercise of that power. But then it's a direct exercise of an enumerated power, and doesn't need to implicate the necessary and proper clause at all. So here's two fails on their part: it's quite reasonable to hold that their bill would be constitutional (although probably really bad politics and really bad policy); but on a basis that has no relevance to PPACA.
There's another major fail on their part, though. In exercising its power to arm the militias, and to raise an Army and Navy, Congress takes tax dollars and uses them to buy guns.
Effectively, the government already does force us all to buy guns, via the IRS, Treasury and DOD. And it's perfectly constitutional.
Oops. Their argument just collapsed, completely.