If you just want the last element
$ echo ${muh[*]: -1}2
If you want next to last element
$ echo ${muh[*]: -2:1}bleh
According to Greg Wooledge's wiki, (which links to the bash changelog) the negative index syntax was added to bash in version 4.2 alpha.
If you do man bash the section on arrays does not list this behavior. It might be something new (gnu?) in bash.
man bash
Fails for me in CentOS 6.3 (bash 4.1.2)