At some point, I'm sure someone at Reaper, during the planning for the Bones III Kickstarter said, "You know, for this campaign, we really have to bring out the big guns." Apparently, someone took that statement fairly literally. They then called up the fine folks over at Victoria Miniatures and said, "So... we need to bring out the big guns for this Bones III Kickstarter." And then the Victoria Miniatures people also took that literally. At least, that's how I hope the decision to add the Sledgehammer artillery piece to the campaign went.
This crossover figure between the two companies will be added to the Bones III campaign when it reaches $1310k. They're currently looking to unlock a set of Pathfinder figures that will be added to the main crop of figures. But they figured showing off the piece, people will go ahead and up their pledge for it if they want (or bring new backers in who might only want the Sledgehammer), and make it much more likely that they'll make it to that goal.
The campaign has 8 days left for you to jump in on it if you want.