We all are really good at selective picking. All those who are in favor of blasphemy punishment would quote the Hadiths mentioned by Last Island and those against it would quote the incidences quoted by me. Twisting the facts and using it for own accord is the agenda adopted on both sides. The conservative would condone the fact that the dear Prophet forgiven whole lots of people who had done blasphemy against it, so we could follow this example. The liberals won't believe that there might be a punishment for blasphemy. The solution lies in between the both situation.

Last island , u said its upon his(PBUH) will to forgive the enemies but not us . Now as he is dead then how could we seek his advice? via Quran and his sunnah, NO? There is a clear cut message in the incidences of Fateh Makkah that IF the person ask for forgiveness and regret his bad deed forgive him. But what to say about forgiveness people won't even care to see whether the person alleged has actually committed the crime? Even there is an incident when the Judge was killed because he freed the alleged criminal on lack of evidence.

My conclusion is IF Islam favors the blasphemy punishment then sure carry on with it but only after the assurance that the punishment being given only to the person who has actually committed the crime. Else, it might happen then instead of getting reward we all ends up getting the punishment because Allah the Just would not forgive such act. And the right of repentance should be provided to the alleged person as provided by dear Prophet and Allah the Merciful. If someone deny the charges of blasphemy let his case be rest to God and we shouldn't play the role of God to declare the prophecy of right and wrong on other person just on our own accord. Because Allah is the final decider and HE knows the best.

P.S : I'm waiting for the full reference of the last Hadith quoted by you

Regards