The Two-Handed Index Finger Point is an excessive, nonverbal signal of grandiosity speakers will use only in front of a crowd they know is already on strongly on their side. With rare exception, in a political context, you will only see it when a candidate is stirring up his/her political base. People use this gesture when they want to foster a self-righteous emotional tone in the audience. If used in front of a neutral or negative audience - such body language would cause people to boo, leave or it may even incite violence.
If the two-handed index finger point (aka double pointing) is used often, particularly in different settings, it can be a signal of narcissistic tendencies (I don't mean to suggest this applies to Mr. Romney, he uses it rather sparingly as politicians go).
Mitt Romney won both the Arizona and Michigan Republican Presidential Primaries tonight. Michigan in particular was considered crucial for the former Massachusetts Governor. He was born in the Great Lake State and his father (George Romney) was a three term Governor there as well as CEO of American Motors.