Is this such a bad thing?
If developers are targetting a line of business app inside their enterprise they probably know what the mix of desktops are... and can decide to use OLE automation of they want (after all, there are some cases where they may need that and as AIR doesn't offer it then it's the only way to give them the option short of writing a native app)
In the interwebs developers can choose to expose scenarios requiring OLE automation if a user is running Windows in just the same way they offer different browsing experiences today.
The browser differences... while it would have been really cool to see Silverlight include the IE9 rendering engine on Mac and PC or maybe host Webkit I think using the local experience is great - it minimises the runtime download, it offers a familiar experience and really how much difference is there between Safari and IE8 rendering? I agree that the missing ability to host HTML in Silverlight inside a browser is a loss... but I suspect they are worried about recursive nesting sucking the entire Internet into a single Silverlight object on a web page and then where would we be!
Linux, for all it's squeaky wheel protestors, is still a server OS. how many typical users are running it today as their primary client (remember ... if you're reading the Reg you're not the majority of the audience) - and anyway... Penguin fanciers made an informed decision so they can't really claim shock and surprise if an app doesn't run there... heck, Photoshop doesn't either but where's the Adobe vitriol! Anyway... if they're as smart as they claim to by... why not help Miguel finish Moonlight then they can have their Silverlight cake with Open Sauce.
Nice to see El Reg covering PDC but not sure I get the negative spin on everything... this story, the one about Be A Martian (http://BeAMartian.jpl.nasa.gov) etc make me suspect some News of the World bias is creeping in....