If civil partnerships, civil unions and whatever other name given to the institution are synonymous with marriage, then call them marriage. I don't believe in separate but equal because that's rarely the case. We've already had that fight in this country.
Let's just imagine for a moment that marriage and civil unions are 100% identical in every facet except name. That would still create an emotional "otherness" that's unfair regardless of the way it's labelled.
It would be different if the gay community said "we don't want to mimick straights and have the same name to our unions." What we have is a situation where the fear mongers, the frightened and the just plain ill-wishers (for lack of a better term) are forbidding this.
Still, I'm grateful to live in a time and place where this is now a part of our dialogue. Things will change. Oops, did I inadvertently slip the campaign slogan in there? hehe