Experiment for us and report back.
1.) Use good, brand name (read: Philadelphia) cream cheese. Wal-mart brand does not seem to work too well.
2.) Probably would have been wise to soften/melt the cream cheese before putting it (cold, straight from the fridge) in the already reducing sauce.
3.) I could use an immersion blender--lots of little bitty white clumps of cream cheese now. Hopefully they will melt.