Pepsi/iTunes Update:

Well, I am now a whopping 2-for-2: 2 Pepsi's bought, 2 free iTunes songs won. It's a pretty cool promotion, with 100 million free songs (1 in 3) being given away. I must confess, though, that the two Pepsi's I've bought probably wouldn't have been purchased if it wasn't for this promotion. If you are a regular Pepsi drinker, check out this article on how to never lose Pepsi's iTunes giveaway.
For the rest of us, though, here are some thoughts:
Ok, so let's think about the math here. One song from the iTunes Music Store costs $0.99. One 20 Oz. bottle of Pepsi costs more (forgive me for not remembering how much). So sure, you're getting 20 Oz. of Pepsi AND a song for much less than their combined costs, BUT -- if you aren't a regular Pepsi drinker then you're really just paying more for a song. So, here is what I recommend. Every time you see a Pepsi with the yellow cap and are tempted to buy one just to win a free song, DON'T. Instead, just go home and buy yourself one song. It's that easy!