While I do believe Blair lied, I don't believe he knowingly lied. Allowed himself to be convinced by suspect data is not in my mind a good enough reason to impeach someone.
There is definitely a case for a debate in the house on whether Tony Blair lied and on whether a public apology should be forthcoming and whether some accountability is required.
My problem with this approach is that it's likely to entrench pro Tony forces as oppossed to bringing the true and accountability back to government. It'll never get to the house as an impeachment motion, a debate on the issue might have.
Paul.