I saw a twitter log from someone mentioning that he couldn't download Flash Media Interactive Server 3- Developer Edition, that was released yesterday. I tried it this morning, and happened to have the same problem.
The 'Download Adobe Flash Media Development Server 3' page shows up, and and it doesn't show Flash Media Server download bar, but lists Flash and Coldfusion as related downloads.
I went to the downloads homepage and tried it again, and this time the page reloaded, with 'ADobe United Kingdom on the titlebar'. And I noticed that the locale in the URL changed to en_gb now, and the download was available! Looks like, Adobe doesn't want US developers to download FMIS yet ;o)
Here is the url that works: http://www.adobe.com/cfusion/tdrc/index.cfm?product=flashmediaserver&loc=en_gb
This, am sure is a temporary issue. Hopefully Adobe will get this fixed in by the time you read this post ;o)