I would love to be able to edit forum posts! While I don't think it would be right to have the ability to delete them entirely, it would be nice to edit such things as misspelled words, to add a thought to the post, or even to go back in and clarify something that was said. This could be done in fairness by simply showing a strikethrough through the original content that has been edited, or even by auto-generating a date and a time on the edited post itself reflecting the date/time of the most recent edit.
Users who wish to make a point of keeping a forum authors "original point" for whatever purposes would have the ability to use something called a [quote] feature which would maintain the original quote in its integrity. I think this is extremely important in the case of disagreements or debate, one should not be able to leave a comment, then delete it if it offends someone or spawns heated disagreements. The post would most definitely wind up looking one sided! lol!
I dunno, I for one always leave few follow up blips if I say something stupid like free sex, versus free sex TOYS, or if I want to add a link (and forgot it). lol!