Personally I'm not surprised. The shows that were available in AMP did not really appeal to me and the format of a desktop media player was also not what consumers seemed to want or indeed need - Joost anyone? The 'iTunes for video' concept simply did not catch on.
Strobe, the new media player framework that was recently announced, now appears to be taking center stage and is being pushed as the way forward when it comes to building media players (initially for the web but we all know how easy it is to turn a Flex based application into an AIR based client), and the coverage on NewTeeVee seems to suggest that even Adobe had their problems when building AMP, contributing to the birth of Strobe.
R.I.P. Adobe Media Player, I won't be missing you though.