Bosworth, the nephew of Brian Bosworth, was originally signed by the Broncos following the draft, but he was waived back in June. ESPN's player page for him has his most recent team as the Jaguars, but I haven't found if that's accurate or simply confusing him with his twin brother, Kyle. Kyle Bosworth is on the Jaguars roster as well, but I don't think Korey ever was.
Another interesting thing is that Korey Bosworth is listed as a linebacker on some sites, but he played defensive end at UCLA. I would imagine that he was a linebacker with Denver because they run a 3-4, but with the Lions I'm guessing he ends up at DE to fill the void at the position created by yesterday's move to part ways with Jason Hunter.
To make room on the roster for Bosworth, tight end Richard Dickson was waived/injured. Dickson hurt his knee against the Steelers on Saturday, and I would imagine that is the injury that that he is being waived with. (If he clears waivers, I believe the Lions can put him on injured reserve.) His chances of making the roster were slim to none with there being so much depth at tight end, but he was reportedly having a good camp and seemed like a practice squad candidate to me.