The way I see it, the Fed has put the economy in a lose-lose situation. If they abruptly halt their QE2 efforts upon reaching the $600B threshhold, I would anticipate the artificially pumped up stock market to begin deflating quickly not to mention running the risk of the Treasury not being able to sell all its new and rollover debt to foreign parties in the bond market.
If the Fed continues to inflate by continuing to buy Treasury bonds with funds beyond the QE2 $600B they will add to the depreciation of the dollar ala Weimar Germany putting us closer to a high to hyperinflationary situation somewhere in the foreseeable future. JMO.
The only saving grace we have is to cut the budget and cut it radically and get rid of deficits, and preferably start running surpluses. We then need to revise the tax code as well as get rid of ridiculous regulations so we can muster a tax base again to facilitate surpluses.