Do they offer payment confirmations to a user specified reporting url?
Edit: Yes. They call it a Receipt URL. It is in the merchant tools section.
That would enable easy bitcoin integration with webapps without running your own bitcoin server. Probably you'd need to call their server back to ensure that the report really was from them. That's how ZayPay does it.
No need to call back to their server. They PGP sign (optional, you can switch it off) the posts to the receipt URL on my end. The downloadable toolkit "just worked" out of the box for me. I had to muck with GnuPG a bit first. Hell, I can even have them post the receipt data over Tor to my .onion address if I were really paranoid.
I was pissing around and I found privacyshark is using their new merchant interface already. They have their domains priced in dollars, when you go to place an order mybitcoin is converting it to BTC on the fly.
I used to sell stuff with e-gold back in the day, and I'll tell you, customers don't want to buy things priced in grams of gold. They can't wrap their head around it. Price it in USD (or EUR, whatever) and they understand it instantly.
mybitcoin's site lists this feature (main page) as "currency comparison". lol! I bet they didn't want to use the terms conversion or exchange anywhere on the site.
I'd really like to see statistics. I wonder how many transactions happen @ mybitcoin per day/hour/week.