Ahhhh! Intellectual property discussions! Run for the hills!
...But in all due seriousness, I really only chose this license because it's the most strict one OpenGameArt provides (and even then it isn't very strict). I really won't mind if people try and pawn this tileset off as their own, because they really wouldn't be able to do it when it's out there for free.
Anyways, new update coming your way!
== UPDATE 2/9/14 ==
- Blood, slime, water and lava splatterings.
- 20 new magic effects and 2 rope effects.
- 3 new walls (smooth, shiny, crystalline) with accompanying pits and palettes.
- Tons of new aquatics, humanoids, quadrapeds and other creatures.
- Created new "Avians" category and shortened all file names.
- A few more pieces of decor including 6 candles and 8 beds.
- Farmland with 16 accompanying crops and food.
- Stone walls, 4 villages, 4 castles and 4 bridges for overworld.