Really? Are you in enterprise software or something? We (WePay) see less than 1% of our traffic and revenue from IE<=7, and that includes the data from our embeddable checkout flow. And of that tiny amount, most is related to our API.

We still officially support 7 for our offsite/embeddable stuff, but from the chatter I hear of the devs that are working on that stuff, the maintenance cost sounds higher than the revenue. Then again, that cost to us is yet another reason that people like our API, since its one less tedious thing for other devs to worry about in their checkout process.

International ecommerce, including China, I can't speak to the exact numbers but the revenue from 6 and 7 is in the millions so we're not quite out of that maintenance cost to revenue hasn't quite tipped yet. Though we do display the ie6countdown.com banner along (and I may have messed it up a bit to display for 7 as well.)