Eventually we'll start seeing ecommerce sites able to build in the bitcoin payment handling, but even this method works for now. Thanks for adding bitcoin as one of the methods!
Agreed - this part is huge. I am happy to see even more carts supported
https://en.bitcoin.it/wiki/Category:Shopping_Cart_Interfaces over time - the big win will be as soon as a major provider (like Google Checkout) comes out with built in BTC integration.
At this point, I think as long as all the major ecommerce platforms supported BTC then adoption would be fairly quick. I don't know of a single merchant that doesn't hate their card processor - but it's pretty much a monopoly between the credit card companies/paypal right now.