They have obviously just woken up to the fact that they were about to lose the PR war by not accepting the proposals of the quartet. That doesn't mean that they believe for one moment in the objectives of the quartet - it's all about posturing and tactics. The strategic decision to bring about the ultimate destruction of Israel remains unchanged. They are are just refining the tactical manner in which that can be achieved!
Australian Islamic State recruiter killed in U.S. airstrike in Iraq (Reuters)
from the article: Palestinians: Quartet peace plan contains 'encouraging elements'