Hybridization problem about guanidine.

[abcd8989]

Structure of guanidine is as follows:
http://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Guanidine-2D-skeletal.png/800px-Guanidine-2D-skeletal.png
The central carbon atom is obviously of sp2 hybridization and there is 1 unhybridized p orbital remaining. I suppose that the N atom doubly-bonded to C is of sp hybridization and the other 2 N atoms are of sp2 hybridization. Am I right?

[DrDu]

First I want to express my general objections against saying that an atom "is" sp however hybridized.
Having said this, I would like to remind you of the free electron pair on the N with only one H attached to it.