The NFL Network's Albert Breer tweeted out the news.
Steelers activate OLBs James Harrison and Jason Worilds from PUP.— Albert Breer (@AlbertBreer) August 28, 2012
While the Steelers will also welcome the presence of Jason Worilds back to their linebacking corps, it is Harrison's return that should make the biggest impact.
The 2008 Defensive Player of the Year, as ESPN's Jamison Hensley points out, "is targeting to play in the Sept. 9 regular-season opener," but that, "some believe it's very questionable" he will be on the field for their opening game, which is against the Denver Broncos.
Harrison, 34, had his knee scoped about two weeks ago. That came after his knee kept him from participating in any of the Steelers' training camp.
So Harrison not only has to get his knee healthy, but he has to get into football shape after having zero training camp in less than two weeks if he wants to take the field for the opener.
That is a lot to ask, even for a great and durable player like Harrison.
If he does make the field in the opener, I would expect his role would be limited to spot pass-rushing duty. This will allow him to get his feet wet, get his legs back under him and likely get reacquainted with Peyton Manning.
That said, the Steelers would be wise to make sure Harrison does not rush back. They can't risk his presence in one game at the cost of him possibly re-injuring his knee or another part of his body while he compensates for his knee.