Per Schefter:

Adam SchefterVerified account@AdamSchefter[URL="http://www.planetsteelers.com/AdamSchefter/status/316254567769714688"]13m[/URL]James Harrison's agent, Bill Parise, said he has not closed the door on his client returning to PITT and would welcome a call from Steelers.
There is also a story from PFT.

[URL]http://profootballtalk.nbcsports.com/2013/03/25/harrisons-agent-declares-door-open-to-steelers-return/[/URL]

I thought that somebody would give James Harrison a 2-3 year deal where he would have made more than the Steelers offer, at least in the first year. Looks like I was wrong, and I'll gladly admit that.

Now that James has an opportunity to see his market value, perhaps there is room for an incentive laden deal.

I was doubtful that Harrison would return and still am doubtful, but the coaching staff wanted him back, and if they can work something out, I would love to see Harrison back for one more year. Between his age and Woodley's injury history, I suspect that the Steelers will still end up with an opportunity to see what Worilds can do.