I think Prezi could really benefit from allowing users to group objects and move them in mass. Without this kind of feature making edits to presentations is really time consuming.
that function is already there: hold the SHIFT key to drag a frame around the objects, then move them in unison.
Marking this as solved since this feature already exists.
We actually have a great article online that was written for grouping with screenshots to help you with the solution.
You can check it for yourself at - http://bit.ly/1nHePmS