I have been looking for a good case to carry my 8100 while I am jogging (using it as an mp3 player).
I went to best-buy and it seems that the XM Radio Nexus is about the same size and is actually unobstructed where the opening is for the earphones and the volume buttons. It looks like it will hold it pretty well, even if the perl is a little smaller. I'm not really sure I like the 'styling' of it, though.
Here is a link to the item: Sports Armband for XM NeXus
I think it is a godsend, until the real deal comes out. Anyone tried it yet? Or shall I be the first?