Okay, so I was testing out a silly new set and I believe I discovered at least 2 problems with the move 'Natural Gift' (which makes 3 if the other folks are right about its incorrect damage output, I didn't test that).
I was using Driflblim with Unburden, carrying a Liechi berry. I used Natural Gift. The attack was successful, in that a grass type attack hit my opponent. However, I did not receive a +1 att boost (the berry's effect) which Serebii suggested I would. I went to Veekun before posting this, but there's no mention of whether you'll receive the berry's effect when using Natural Gift (and in addition, no list of berry effects at all on the Natural Gift page).
The second issue is that I did not receive the Unburden speed boost. The berry was certainly gone, as evidenced by the fact that Natural Gift failed from that point on (also different from Serebii's analysis) and the fact that reaching 'a pinch' did nothing.
These two problems (and the damage inconsistency, if it exists) are really hurting my completely brilliant Drifblim sweeper.
EDIT> Adding a replay documenting the bug:
http://replay.pokemonshowdown.com/customgame-76306943
I tried to make it as obvious as possible, but I think you'll just have to take my word that I'm running Unburden on the Drifblim