Forced movement can go to somewhere you can't see but not somewhere you have no Line Of Effect too. (Ref: Rules Compendium, Pg 211-213: Forced Movement).
So being blind or pushing into darkness is no problem, but pushing (or pulling or sliding) around corners or around pillars is no go.

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