Something that has come up a few times before on the mssms email list has been the ability to modify task sequences in an automated fashion. With ConfigMgr 2007 it was possible to export/import task sequences as it was straight XML. With 2012 its a little more difficult but you do not have the ability to modify an existing task sequence. If you import using straight WMI or the Import-CMTaskSequence it creates a new task sequence and not not allow you to overwrite or modify an existing one.
Please vote to add this functionality to ConfigMgr!