[jessaustin]

So much for Amazon's risible old saw that "sales taxes vary so much among jurisdictions that calculating taxes would be an onerous burden for us". There is some business size at which that is true, but Amazon has never been that small. Lots of folks use Vertex: http://www.vertexinc.com/solutions/indirect/sales-tax.asp

Since Amazon has been growing its SaaS business for some time now one had to expect they were eventually going to want to make operating shopping cart checkout by yourself as tricky as possible. They might start lobbying municipalities to pile on the complications now that they're on the "right" side of this dispute.