Well I am going to fully admit that my heart is leaning against the call because hey, I'm biased. I'm putting that out there because as I repeatedly watch the replay I keep coming to the conclusion that Lupul didn't do anything wrong. When I watch the replay I don't see how Lupul interfered with Michalek in any way. All I see, at the
42-second mark of the video (that provides the best angle IMO) is Lupul minding his own business skating backwards and not initiating any contact, whether it's interference, pushing, or shoving against Michalek. What I do see is Michalek giving a very very light two-handed shove to Lupul's back, and I guess since Lupul remained firm the shove, perpetrated by Michalek, ends up propelling Michalek into his own goalie.
edit: And yes, after re-reading this post I realize it sounds like a lot of spin. =p