So I was following the documentation at http://www.slony.info/documentation/2.0/failover.html and couldn't figure out why i couldn't switch over.   I kept getting an error about node -1. I found http://www.slony.info/documentation/2.0/stmtwaitevent.html which says "In version 2.0, the default value for WAIT ON was removed, so a node must be specified."  Adding wait on solved the 
problem.

Something else I noticed is that tools/altperl/slonik_move_set.pl does this with slightly different commands, it does:

lock set (id = 1, origin = 1);
sync (id = 1);
wait for event (origin = 1, confirmed = 2, wait on = 2);
move set (id = 1, old origin = 1, new origin = 2);

whereas the example in the documentation does:

lock set (id = 1, origin = 1);
move set (id = 1, old origin = 1, new origin = 2);
wait for event (origin = 1, confirmed = 2);

I'm not sure if sync() is required, but I'm using sync() in my scripts, it seems to make sense.  I'm also doing a wait for event after the move set.   Something else that might be helpful is showing how to switch back.  It's not immediately obvious which node ids should be used for the wait for event commands.  I think the opposite would be:

lock set (id = 1, origin = 2);
sync (id = 2);
wait for event (origin = 2, confirmed = 1, wait on = 1);
move set (id = 1, old origin = 2, new origin = 1);
wait for event (origin = 2, confirmed = 1);

Thanks,
Brian