UPDATE: Amazon has come out in support of the new Internet sales-tax bill. See quote below.

The Marketplace Fairness Act, introduced today by a bipartisan trio of senators, would require all but the smallest online vendors to collect sales taxes from their customers.

Currently, under federal law, states cannot force sales-tax collection on online retailers that do not have a physical presence in their state. Of course, brick-and-mortar businesses have long been required to collect sales taxes. The bill would mean a more equal footing for online and offline businesses.

This bill is an updated version of the Main Street Fairness Act, introduced earlier this year, which eBay opposed because it required all online vendors to collect sales tax. The company felt this unfairly penalized individuals and small businesses, which make up the bulk of its auction business, tech news site PCMag reported. In an interview with our sister site, The Consumerist, eBay's Vice President for Government Relations and Deputy General Counsel Tod Cohen said, "This is another Internet sales tax bill that fails to protect small business retailers using the Internet."

Amazon has confirmed its support for the bill. In a statement, Paul Misener, Amazon vice president, global public policy said the the following:

Amazon strongly supports enactment of the Enzi-Durbin-Alexander bill [Marketplace Fairness Act] and will work with Congress, retailers, and the states to get this bi-partisan legislation passed. It’s a win-win resolution.

Several states have already gone ahead with so-called "Amazon laws," compelling e-commerce companies with a presence in those states to collect sales taxes. This past May, Amazon founder and CEO Jeff Bezos said that federal legislation was required to address differing state policies. Amazon then fought a law in California, delaying the collection of sales taxes in that state until September of 2012.

Previously: More online retailers collecting sales tax, industry group says

Marketplace Fairness Act
Senators Introduce Bill To Compel Amazon & Others To Collect Sales Tax [Consumerist]
Compromise Internet Sales Tax Bill Expected Wednesday [PCMag.com]