Rob Neyer had a post on SB Nation also giving Rendon props, but he goes in depth, saying if Zimmerman is going to stay at 3B ... NOW is the time to convert Rendon to 2B/SS (he thinks 2B will be his landing spot, as do I).
His argument is that Rendon could be ready by 2013, so it's better to get him going on a new position now, because he's so close.