love the illustration but http://www.threadless.com/submission/31802/inky
looks like it's been done. i like your octopus more though, it's better executed than the other. if you made a vector of it ib et it would look clean as hell. cool graphic. cool colors. cool tee.
i don't like your other ones, but i love this one.
don't vector it, whatever you do. it would look like every other threadless shirt where someone's sat down thinking "what can i put on a t-shirt?" this one looks the opposite way round - like you've drawn something & then thought "shit, that would look good on a shirt". and you were right.