Freefall has had a succession of "guest robots" in the background, starting about here in March with Huey and Dewey from Silent Running. I'm amused by seeing them all there, and I like that the artist is having fun.
What grates on me a bit is that he includes a copyright notice for each robot--- dated 2007. In no case do I believe this date is correct. I'm not sure whether this is ignorance or a political statement. If a character is copyrightable, then that copyright should date from the original publication of the character. (I admit that it's a bit fuzzy when you redraw or reimagine a character... but surely there is "something" that has a fixed copyright term, otherwise you could game the system by inserting a new typo or visual glitch into your work every year.)
But, I don't really expect Mark Stanley to do the research to put the correct copyright date on. (I believe his doing so is merely a courtesy.) But (Congress willing) at some point characters will start entering the public domain. And at that point the copyright date becomes very important. And there is going to be very little we can do to identify what's legal and what's not.