Heh, that's pretty interesting.
As far as game mechanics go, I don't see much resemblance, so it must either be a different kind of link, or a Spelunky fanboy/girl put it up there while high.
It's possible that the creators of Terraria did in fact take some inspiration from Spelunky, however.
[Kinda Off Topic]A game I've been watching the progress on that's quite similar to Terraria is King Arthur's Gold
, which had it's first open beta released before Terraria was released, and so was quite disconnected. However, any further discussion along this line should be moved to a topic outside of the Spelunky board.