Compendium said:Climb speed
A creature that has a climb speed moves on vertical surfaces at that speed without making Athletics checks to climb. While climbing, the creature ignores difficult terrain and doesn’t grant combat advantage because of climbing.
Compendium said:Acrobat's Trick
At-WillMartial![]()
Move Action Personal
Effect: You move up to your speed -2. During this move, you have a climb speed equal to your speed -2. You also gain a +2 power bonus to your next damage roll with a basic attack during this turn.
I think it's the same principle as when a racial power, class power or item gives you a fly speed until the end of your turn: at the end of your turn you fall unless you're standing on a solid surface.
I would rule this power the same way, despite the lack of an extra sentence. I just think this is consistent with how 4E/4.5E treats special movement.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.