So today my little sister, who mains Zelda, was fighting my crewmate (don't worry, my little sister is pretty legit) and something weird happened. She UpBed, but got a HUGE lateral momentum boost backwards before she actually teleported. It was impractical at the time, but seemed potentially useful if it can be replicated and mastered. We captured the replay. I can't upload it, but I will send it to a Zelda who is interested in uploading the footage for the good of the Zelda community.
I believe she accidentally performed a "wave-bounced" UpB (pretty difficult stuff here) which may give Zelda a really pretty boost in her upB. She moved a considerable distance backwards away from FD (she was above it and offstage, about to recover laterally) before she actually teleported, when she activated the move. If this is done backwards, you could move significantly towards the stage. It might also be used to recover from some hard to reach places, or just used in mid-combat as an escape.
If you're interested, PM me your Wii Code and Brawl Code, and take mine from the left of this post.