I dont know where these people are getting their information from but you can for sure back up virtual console games on sd cards. Im pretty sure u cant play them on other wii systems, i dont think nintendo would be that stupid, they would lose some profits from people sharing, and if they posted the files online, lots of profits. they would only be backed up for your use.
As for the emulation thing, ive tried simply running some roms on the wii but it doesnt work because its not read as a virtual console channel, it doesnt even have the right file extension. Also there is a significant difference in memory sizes between standard roms and the virtual console files; my guess is that they package an instance of the emulator for that rom separately with each rom or else that extra data is what allows the wii to run the games and verify what they are.
theres probably a way to convert standard roms to the right format but since the games u download are tied to each console, the verification might be a tad tricky to deal with. Im still a lookin for a way.....
my main reason for wanting this is cuz they havent released many decent titles on their virtual console yet, i really wanna see loz: link to the past, and some nice third party games!!!!! in the meantime i have to sit and wait