Williams is not big (5'11"), but he can play several positions and is a right-handed shot.
Jason can provide some excellent depth at the forward spot. He has been a decent goal scorer in his career. In fact, he was a very good player for Columbus in 2008-09 for the second half of the year and then signed with Detroit in 2009-10. He fractured his fibula on November 9th of 2009 and his numbers haven't been the same since then.
He didn't sign a contract in 2010 until December, and then it was with Connecticut of the AHL. Dallas signed him last February and he played 27 games for them to close out the season.
When you see such a quick, sharp drop off for a guy, you have to wonder if it was the circumstance in Columbus that allowed him to succeed, or if the injury to his leg changed his game.
Either way, this is a great low-risk move by Ray Shero. Williams will have a chance to make the team in training camp, I'm sure, and will be one of the first considerations if there's an injury.