I remember finding it in my sister's record collection and playing it non-stop after that.
My 2-cents: I think kids, especially boys and young men, might be re-discovering rock after being subjected to so much musical crap for the last 7 or 8 years. The primal sound of Zep is definitely a guy thing.
I think some of it is the bands like Wolfmother who wear the Zep influence much more clearly than 90's bands did. Bands like Soundgarden and Alice in Chains were certainly influenced by Zeppelin but it wasn't as clear. Mostly because their lyrics were a lot darker and introspective than "squeeze my lemon until the juice runs down my leg". Not that that particular line isn't profound. :)