A developer and his team from the Mono project were offered by Microsoft a 10 – 20 minute presentation on the Mono project's efforts on bringing Silverlight to Linux. As all they had working at that point was a rectangle that could move a bit and not much else, the team decided that they would stage a 20 day hack-a-thon to complete as much Linux XAML implementation as possible before the talk which was going to be 21 days later.
At the SLIDE7 event a Microsoft speaker said that they were developing the Silverlight plugin for both Mac and Windows; IE and Firefox — but not for Linux, as there was 'not enough demand' for it.
It'll be great to see the new 'Moonlight' plugin for Mozilla when the first few alpha or beta builds surface.