I am all for that, I love my sirius & it would make the N800 a true killer device for me.
I'd gladly donate a few bucks, or help develop if at all possible (though I have no clue where to start).

There is an open source Sirius add-on/extension for Firefox that works well, it may be good source for ideas or maybe the developer of that project could be swayed to porting it to the N800/Opera ??

Check it out here:

http://dev.megagram.com/sirius/