Is her Q bugged? I thought they fixed that on the Test Realm.
Her ult is still fantastic for tower diving, but yes it's not a get away free card. I'm not sure if her passive will be nerfed: that's somewhat the point of it xD. I personally don't feel it should affect certain spells (notably Cho's ult), but that's because I'm biased from DotA, where Axe's ult worked that (no matter what, if they were below the 'feast HP', they died. The sole exception to this was if Puck phase shifted the instant before Axe cast it.
Alistar is AMAZING. However: he should not be played as a tank. It'll win you games at low Elos, but at high Elos he's much better as support. The core item on him is sheen right now. He does not need mana regen early game (he shouldn't really be spamming his heal spell at that time). You are exactly right that his flash/pulverize/headbutt combo is his signature move, and it is DEADLY. The main reason Alistar is so deadly is that the knockup and headbutt at uncleanseable.
@Zeraph: While I don't think it's in need of nerfing, Poppy's passive for sure isn't useless.
http://idunnolol.com/lol/poppycalc.html is a handy tool that'll show you against -normal carry dps- how many extra hits it takes to kill her. But you're right that she doesn't have the survivability of the tank; its just measured in a few extra hits to kill her (which mostly matters in 1v1 situations).
@ManWithaPlan: IRC consensus is that Zeraph's interpretation of the passive is correct.
@Zeraph again: Ult, or passive? The passive works the way you described it, the Ult is entirely different.
@MWaP: A 1000 damage attack will have the 900 portion reduced by 450, so she'll take 550 damage. As for the current health, as far as I know that's not how it works.
Man I'm having so much fun WRECKING with free Udyr this week. Lawl. Riot is facepalming, they might hotfix him soon. Protip for easy wins: solo mid Udyr, max turtle stance first. Don't be aggressive til at least level 3.