dstiles - 9:50 pm on Sep 12, 2012 (gmt 0)
I agree the software is more robust in that it is difficult to install non-repository software but a lot of viruses are "social" - clicking on links in FB, in emails (because the default is "view as html"), clicking bad links in SEs (yes, they do exist!) and following stupid links on a suspect web site. If the link/whatever carries a multi-platform installer then it IS possible to install viruses on linux.
Linux can mitigate these but I do not think it can entirely prevent human stupidity.