(written from a Production point of view)
Round 2 LLC is an American company, founded by entrepreneur Tom Lowe in 2005 and based in South Bend, Indiana, that specializes in model kits, toys and diecast collectibles. 
In 2007, they purchased the Aluminum Model Toys, Polar Lights and MPC model kit lines from their prior owners, Racing Champions. Round 2 LLC relaunched each of the product lines under their own original brand names, and for the first time in a number of years, all US-licensed Star Trek model kits, marketed since 2007, were being produced by a single company.
Round 2 markets their model kits internationally and has only once sub-licenced a limited number of their kits to the Japanese model and kit company Platz, which marketed four kits in 2010 under the combined name "AMT/Ertl-Platz" for the Japanese market only. The only other company that as of 2012 holds an official license is the German Revell company, which managed to extend the license it held for the Star Trek: Voyager model kit line as well as new products originating from Star Trek: The Original Series, albeit for the European Union only. The status of the license of the Voyager model kit line, originally held by the American Revell-Monogram company, is as of 2012 unclear, as no Voyager model kits have been marketed in the US since 1997.
Some Star Trek-related Round 2 brands were exchanged with Tomy, the current owner of Racing Champions (RC2) in 2011.