Well I think Vertigo is probably an introduction of sorts.
The 'vertigo' in Vertigo is an emotional/mental one. It's in the first verse. He's caught in between his head which is telling him one thing, and heart which is telling him another, and thats where the vertigo comes from.
The opening verse is kinda confusing, like you don't know which one won; the head or the heart.
The jungle is your head, but it can't rule your heart, which is really strong, and your soul (heart) can't be bought, BUT remember that your mind CAN wander... See, I'm confused, I'm at a place called vertigo (Dond' esta = Where is it?) It's everything I wish I didn't know (head), but you give me something I can feel (heart).
What the argument is between his head and heart I don't know. It could be temptation. It could be a spiritual argument. It could be the life Bono's lived over the years since ATYCLB.
Remember at the time of recording ATYCLB Bono was involved with the Drop The Debt campaign, and ATYCLB was influenced by the themes in that campaign, fresh start, optimism for the future etc. It (Drop The Debt) was a very forward looking, happy campaign. Since then there's been the massive Elevation tour, death of his father, 9/11, Iraq, and his much, much larger campaigning, lobbying etc for Africa. The current African campaign is different. It's based on mass tragedy. It involves from Bono a lot more in regard to lobbying, fighting, deal making, and I think he probably has a very strong sense of the importance of his position in this campaign, like he says, he's "working for the African people", he's the face, heart and soul of the campaign. That would weigh very heavy. What if he fucks it up? What if it all succeeds?
I think he's probably seen more of the 'real' political world as well. What lobbying involves. Attitudes towards Africa. Obscene amounts of money being allocated for trivial things, and war, but not this issue. Despite all his 'non-partisan' talk, he's definitely playing the political game. This may not sit comfortably. All of these things may create an argument between his head, and his heart.
I dunno, it's Bono so it's multi-layered and it may be one or all of these things. And thats why I see it as an introduction. Basically, Vertigo = "A lot of shit has been going on. It's a spin. I'm not sure what to think about it all." And then, on the other 10 tracks he'll go further into exactly what it is that is going on in his head and heart.