This is an odd coincidence, one of the Dead Man's Switch subscribers asked me if I supported Bitcoin, and I ended up adding a MtGox button on the site (it's pretty nifty, it even autoconverts to whatever currency you want and supports IPN):
I've been warming up to Bitcoin, the same subscriber clued me into https://blockchain.info/ and it looks pretty good. The only thing I'm worried about is that Bitcoin isn't very stable, but I don't really care since MtGox autoconverts all payments. There's no downside in accepting it, as far as I can see.
Plus, I can just keep them as Bitcoins and pay right away with very low fees.
EDIT: I also decided to dabble in a bit of MtGox trading with my newly-acquired 4 BTC, so I sold high and bought higher. It... didn't go very well.
"Autosell" is the term Mt. Gox uses as the name for the parameter in the shopping button API to sell immediately once the transaction has confirmed.
But that's the thing. Merchants are worried about the downside risk, and basically ignore that there is an upside gain possible as well. Sure, the merchant shouldn't be speculating with revenues that go to employee's salaries and inventory purchases, but if there's 10% profit, keeping 10% of revenues without converting that to USDs might be beneficial.
BitPay is a merchant processor that lets the merchant specify what percent of revenue to convert and remainder of bitcoins are paid out without conversion.