Antec has been making computer cases and power supplies for a long time. However, in 2004 they were getting less and less popular with the enthusiast crowd, who at the time was completely in love with Lian-Li and other aluminum cases. Instead of jumping on the aluminum bandwagon they chose another path.
The original P180
I myself was an aluminum fan at the time, never realizing the problems with aluminum as a case material; although light and elegant, noicewise, it is no good. Fortunately Antec took another route with the P180. They were contacted by the most renowned name in hobbyist silent computer systems at the time, Mike Chin at Silent PC Review, and decided to work together with him to incorporate what hobbyists had learned over the years in to a new case: the P180 that was released in the summer of 2005.
Here are a couple of articles on silentpcreview.com, detailing the original P180:
Antec P180: A Visual Tour - an examination of features and design, complete with many photos
Antec P180 Review, Part 1: A Silent System - Ralf Hutter's ultimate silent build with a Pentium-M system
Antec P180 Review, Part 2: The Whole Nine Yards - complete thermal / noise analysis with various components
The P182 upgrade
Two years later, in 2007, the P180 had extensively been used to build a number of very silent computer systems, and acheived the target of very good cooling as well. However, at silentpcreview.com as well as other places, there had been quirks and possible improvement opportunities discovered. Some where taken care of with small updates (one of them sometimes called P180b, as in P180 ver b, not color Black, just to add to the confusion...), but the big ones were collected into a major new revision: the P182.
During 2007 the new upgrades were phased in to the P180 production as well, and now all P180 and P182 are functionally identical.
Here's silentpcreview's article on the P182:
Antec P182 Advanced Super Midtower Case - P180 v.2