I'm not usually one to be all uppity about etiquette. It kinda makes me feel dirty writing this post. That said…
Don't be a jerk.
I actually kinda enjoy gathering guano. So I've done it off and on for ages, gathering a couple hundred at a go, and only very rarely has it been sniped out from under me. I'm pretty good about having it drop right by my feet (or not too far from me). I tend to keep piles forming for a while because it's so very rare that anyone takes it out from under me. Seriously, before today, I could probably count the times on one hand. I doubled that today.
I realize that guano is a hot commodity right now. We've only got one more day to become Yellow Gazillionaires...ohnoes! I know that I should have been more careful with my guano tonight - picking it up every drop or three. And, hey, if it's on the ground, it's free game.
It's still not a cool thing to do.
Remember: The community is what *you* make it be.
(and it's an awesome community, 99.9% of the time, so thanks. you rock!)