Sounds like a good idea to me. I think people might be unnerved at the vast fluctuations in the exchange rate, though.
Yes indeed, but I can't help feel unless we start getting a larger user base (and especially a larger user base of people who aren't just here to trade on the exchanges) then the fluctuations will only get worse, not better. Chicken and egg a bit here I guess.
The only problem I see is that most credit card companies have transactions that are reversible, unlike Bitcoin, and we might run into problems where the user reversed the transaction after receiving Bitcoins. (this is the reason why Mt. Gox and such don't use Paypal)
The reversible charge may well be a problem. But is this much different from paying for 'real' goods with a credit card? Surely the same thing applies there doesn't it?
And as for Paypal... well personally I'd only ever use a 'proper' payment gateway linked to a merchant bank for something like this. I wouldn't touch Paypal with a barge pole.... But that's just me