When you navigate to that URL, you are redirected to the bitcoinarmory.com homepage. If you get rid of the parameters (the ? and everything after it) you get announce.txt as Armory is expecting. The reason Armory isn't running for you is that the program is expecting to receive a Bitcoin Signed Message, but is receiving the Armory homepage.
Okay I am trying with the --skip-announce-check option to avoid that single point of failure (really dumb IMHO to make startup depend upon a specific URL responding in a specific way - what problem are they trying to solve

) and that is no longer an issue, but now it seems to have issues with creating a socket to the bitcoind service.