Content installation (families, templates, etc) has changed for Revit 2012 products. Remember the Content loader/extraction dialog?
This dialog no longer shows up in the 2012 installation. Now you simply choose the content packs you want while setting up your installation and Revit does the rest. If you want to change what content you have installed, you will need to go to the control panel and Add/Remove Programs, choose to Uninstall/Change the Revit 2012 product you want to modify and then, you can choose to Add or Remove Features and choose the content you need installed.
In previous releases, if content installation encountered a problem and didn't complete, when you laucnhed Revit, you were prompted to download and/or install the missing content. In 2012, Revit will tell you that the content is missing, but you will not be able to download it from within Revit. You will need to go to the control panel to add the content back to the installation.
It is important to know that some content may still be downloaded from the internet (depends on if you are downloading Revit or installing from media), so it is a good idea to install Revit with a active internet connection. With 2012, you will not see the download occuring though (no content loader), it is transparent and happens behind the scenes. Your installation may take more time depending on how much content needs to be downloaded as part of the installation.