As far as I know, Zherdev hasn't officially been signed by the Flyers.
From what I understand the Flyers are trying to do something with Gagne before they sign Zherdev. Of course I've also heard that Zherdev is more interested in getting back to the NHL than he is for the money, so he may not be a 3 or 4 million sign, so Gagne may still be on the team.
I'm a Flyers fan, and honestly I think the team is good as it is at this point. The only thing the Flyers should be looking to sign is a goalie. Leighton and Boucher are decent, though a better goalie would never be a bad thing. I'm thinking this won't happen since the Flyers currently have one of the best 6 man defense squads in the league, which will hopefully mean that the opposing team won't be able to get as many shots off, preventing more goals.
Edit: And the Flyers have just made it official that Zherdev has been signed to a one year contract. Not sure on the price of the contract, though Zherdev was reportedly seeking $4 million a year, though I have a feeling it may not be quite that much. I guess Gagne or someone else is going then for sure.