If Hamas and the PLO really wanted peace, they would have continued to pursue peace regardless of a single incident.

At least in the case of the bomb that Israel dropped on an apartment building, it was to eliminate a leader of Hamas, who has orchestrated hundreds of suicide bombings and attacks on Israel was planning more. By killing this one man, who was planning more terrorist attacks, Israel has disrupted and stalled further terrorism.
In contrast, how many Palestinian terror attacks have been on innocent civilians, with no pretense of an objective, beyond spilling as much Israeli blood as possible? They are truly pointless deaths.
Palestinian terror from then until now, and planned to be ongoing, has already killed TWICE as many as were killed in Israel's July 22nd bombing.

If Hamas really wanted peace, they wouldn't have used this incident as an excuse to launch an all-out terrorist assault on Israel, to the point that Israel had to pretty much shut down Palestinian travel in Israel this weekend, due to an onslaught of terrorist incidents:

http://www.washingtonpost.com/ac2/wp-dyn/A44757-2002Aug5?language=printer

To me it just further proves Arafat and the PLO's untrustworthiness as a peace partner, and how quickly an independent Palestine would be used to wage maximum damage on Israel.