RetroPie 3.0 Upgrade Tutorial - Safely Upgrade to the latest version of RetroPie following the steps shown in this video.
I will cover backing up your system in the event something goes wrong, and the two options available to update your system.
Link to the download page for the image based installation:
http://blog.petrockblock.com/retropie...
My recommendation is to do a full SD Card backup, and then go on to the binary based installation.
I hope this helps you guys getting the latest version of RetroPie!