Me and my coworkers find that we want to change where a particular NB
platform points to but the UI doesn't allow editing of that field 
(Tools->NetBeansPlatforms->PlatfromFolder).
One has to exit the ide, hand-edit <userdir>/build.properties, and
restart the IDE.

This usecase arises in the SunStudio group ... We have a constant label,
for example, "NetBeans for SunStudio" that is embedded in our suites.
It usually points to a reference NB location used by our builds.
But we sometimes want it to point to one or more private copies
on an NB platform so we can check against newer platforms,
or own builds of NB or debuggable NB's. 

Creating new labels for each of these platform variations
is impractical because one has to then go an change their
uses in each suite/project and then of course one has to remember
to change them back to "NetBeans for SunStudio".
If you forget you mess up your teammates.

In fact I'll go a bit further and request that a persistent history 
(accessible via a combo-box) be kept for each label so it's trivial
to switch between group build reference platforms, individual copies
or debuggable builds etc.