Well I don't believe I've ever heard a true stereo "remix" of a mono song. Capitol Records in the U.S. famously tried to do this with some of the early Beatles recordings by putting the lower frequencies on one channel and the higher on the other.. just plain silly. You can't get true separation once it's been mixed to mono.
However, you can get the effect of hearing stereo by offsetting one channel slightly.. you can do this in any wav editor and some even have a setting specifically for it. But it's just an illusion :)
I've done it a few times in order to have sound come through all speakers for Dolby Pro-Logic surround, because plain mono sends the whole thing to the center channel only.
I can give you an example actually.. my fake instrumental of It's Late..
Doing this 'karaoke effect' to remove as much of the lead vocal as possible, it leaves you with a mono track, so the majority of this file is mono but using a 'pseudo-stereo' offset: http://rapidshare.de/files/30118108/Its_Late-instrumental.mp3
It reverts back to the original stereo recording at around 3:28 for the guitar solo and then back to mono after. This is because the karaoke effect removed most of the guitar from the solo also, LOL.
As for 5.1, the same rules apply. If it's mono to begin with, the most you can get out of it is sending it to different channels with slight delays or offsets, or perhaps sending different frequencies around.. but at the heart, it's still just the same mono recording. The deepest bass will always go to the subwoofer though, so that can sometimes give the effect of having another actual channel.
When it comes to stereo upmixed to 5.1 mixes, there's a lot more to work with and these can be fairly good.. Queen uses special hardware & software to make these 'unwrap' mixes for things like the Freddie Tribute, Wembley, and even the recent 'Super Live' is not true 5.1 but upmixed/unwrapped instead. Personally I find them pointless because just like with mono, deep down you can't get more than whatever was in the original stereo mix anyway.. and DTS is a huge waste of disc space for something which is fake.. but anyway..
I guess the short answer is yes.. something like the Smile tracks could be made to go through more than one channel and maybe trick your ears, but don't count on hearing anything new, as they will still just be what they are :)
I'd offer to do them in this pseudo-stereo format but sadly I only have the tracks in bad quality 128k mp3 form. Ghost of a Smile is long out of print and on rare occasions when it can be found, the price is ridiculous.