We have been playing around witth the 'Apply System Configuration' task to not only add our machines to the domain, but in certain circumstances also removing them from the domain.
What I noticed was that in addtion to simply removing the computer from the domain it also deleted the computers AD object. For us that meant we couldn't re-use that object to put it back on the domain if we wanted to without recovering the object from the recycle bin.
What I would like to see is a simple tick-box to either allow or disallow removal of the AD object if a computer is moved from a Domain to a Workgroup.