Sales tax is still assessed on a state by state basis, so generally a company has to have sufficient "minimum contacts" (usually a physical presence) to be required to collect sales tax. Many states impose a "use tax" equivalent to the sales tax that you would have paid if bought within a state, on goods shipped in from out of state. I think the million dollar threshold you are referring to is a California law aimed at internet companies.
The bill has yet to pass both houses of Congress. The Senate passed one version, now the House is making their version, and then the two bills will have to be voted on in the other chamber and/or "reconciled." Here's a recent article: http://www.reuters.com/article/2013/09/17/net-us-usa-tax-online-idUSBRE98G11M20130917
There are very few days left in this year's legislative session so I doubt whether anything will happen this year regarding the Marketplace Fairness Act. In addition, I had read that Speaker Boehner has come out against the bill. Unless his concerns can be assuaged, the bill will not ever reach the floor for a vote.
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