Travis Blackley just tweeted:
Perhaps he's not clear on how the August waiver process works. Basically, almost everybody gets put on waivers. When said player is placed on waivers, a team can claim him. If multiple teams put in a claim, the priority is given to the team with the worst record. They then have two days to come to some sort of agreement, or the team that put said player on waivers can simply pull him back. If they try to work out a deal and can't, it's no big deal, everybody just moves on.
So. Either Blackley has been DFA'ed, and just let the entire world know (unlikely) or he is confused about how it works (more likely).