I'm a first-level Druid, and I'm thinking of using my next feat to multiclass into Paladin (specifically to be able to take some helpful Encounter powers later on). Regardless of how smart this is, or how much power/flexibility I will gain/lose, is it possible to use Paladin Encounter powers if I'm in Beast Form?
You cannot use attack powers from other classes while in beast form.
From PHB2, p84 (as updated by official errata):
No paladin powers (or powers from any other non-druid class, for that matter) have the
The exception is if you take the Werebear, Wererat, or Werewolf themes (all from Dragon 410). They all get an encounter version of the wild shape power, and at level 10 that power changes so that it allows the use of powers both with and without the
If you are a half-elf and have chosen an implement power for your Dilettante racial trait, you can take the Wild Dilettante feat (from Dragon 385 and updated by official errata). However, this only affects the Dilettante power and would not apply to other powers you happen to have.
You can only user powers with the keyword "beast form" while you are in your beast form. (PHB2 p 219, RC p 308).