Originally Posted by Crushaholic
I hope Dagobah comes into play at some point. I want to see how Yoda chose to spend his last years there. I'm assuming it's because of the remoteness from the Empire's control, but Luke did say there was "something familiar" about the place.
I think in one of the millions of Star Wars books that exist, one of them says a Dark Jedi crash landed and died there a long time ago (no remarks). His "presence" remains, and with Yoda being a good Jedi they cancel each other out making his presence undetectable to Vader and Palpatine, or something along those lines.
But that wouldn't explain why they didn't know about Obi-Wan.