I always took it that we have the right to those three things (life, liberty & pursuit of happiness) as long as they don't infringe on someone else's rights to those 3 things. H's examples were bad because they would infringe on another's rights to one (or all) of those 3 things. I've yet to see a convincing argument as to how granting homosexuals the right to marry will infringe on somebody else's right to life, liberty and the pursuit of happiness (I smell an abbreviation: ll&poh?).
I guess the retort would be that it would infinge on the happiness of Christians, because if homosexual marriage were permitted in our society then that would make them unhappy because they'd be living in what they deemed an "immoral" society (which I suppose they could also argue that they already are, but I digress)?
I don't know, for what it's worth though I'll announce that I think gays should be able to marry, and that one day they will be able to as society continues to progress. Just like blacks and women are now allowed to do things that they previously weren't, and when we look back on how they weren't allowed to do those things it seems quite silly to us now. I saw a thing on the internet that was a picture of people protesting gay marriage in D.C. and an older picture of people protesting interracial marriage in D.C. The caption was "imagine how silly you're going to look in 40 years." I thougt it was pretty much right on.
*Edit- Oh, and also, just to clarify- I wasn't under the impression that the life, liberty, etc. was an actual right granted to us by law. Rather it's just one of the ideas that we value in this county and is supposed to be one of the things that makes America such a great, free place to live. One would think that allowing people to marry the person they love wouldn't be something that's frowned upon in a free country such as ours. It's been pointed out already in this tread that allowing gays to marry causes no tangible harm or suffering to anybody else, but not allowing them to actually DOES cause people harm and suffering. It just doesn't seem like a very American thing to do.