Basically meant to be equivalent to "Activate one activated ability that you can pay for, from target creature or planeswalker card in your graveyard." Inspired by this comment on Maro's blog.

Yeah, makes sense. Would "If it's a creature, you may activate its abilities as though it has haste" be clearer than granting haste?

"If it's a creature, you may activate its abilities as though it has haste."
"It gains haste but can't attack this turn."

Hmm. It probably would be clearer, but it's a little bit wordier.

Why not just Feldon of the Third Path: The Sorcery?

As in, why return the card rather than make a token copy of it? Shrug. The flavour fits better if it "is" the original card rather than a simulacrum.

Out of curiosity, were there any previous questions about reanimating planeswalkers on the blog or just the suggestion that it should be red?

This means that Venser, the Sojourner can save himself, right?

Haha, yes, Venser, the Sojourner can save himself. Maro gets his wish at last :)

There was a short conversation on the blog asking which colours get to reanimate which kinds of permanent.