Does the Taxing Clause Give Congress Unlimited Power?

The idea has gained currency that the Taxing Clause in the Constitution gives Congress the power to do anything, or almost anything, that would be funded by taxation. Most recently, that argument has been advanced in connection with the litigation about the individual mandate in the Obamacare legislation — by, among others, legal philosopher Ronald Dworkin. If the penalty for failure to acquire suitable insurance will be a tax, then, it is argued, the requirement to acquire insurance, the mandate, will itself be a valid exercise of the taxing power. If that's right, it certainly isn't obviously so. Since almost everything the national government does is funded through taxation, that understanding would lead to a conception of congressional power that is effectively unlimited, and the Taxing Clause would trump almost all other grants of congressional power in Article I, section 8