Effective June 1st, the so-called "Amazon Tax" became effective whereby NY State requires all e-Tailers running affiliate marketing program (that contains any affiliate in the state of NY) to collect sales tax. Beyond the fact that this law contradicts with the consititution (no sales tax on interstate commerce law), there is no provisioning to verify if a customer is actually referred by an affiliate in NY state.
For example, I saw a deal on 8GB Sandisk Cruzer Jumpdrive tonight via Techbargains.com; I clicked through its link and placed the order. To my knowledge, TechBargains is a California-based affiliate; yet I am charged with a sales tax. There is no involvement with any affiliate agent in the state of NY with my transaction, however NY state wants a cut. Amazon.com is not taking this one sitting down, NY Times have a nice article here. I certainlly hope other major e-Tailers take a stand as well.