Mr.Wayne, I asked my friend working at the Department of Foreign Affairs (DFA) to confirm, once and for all, what the actual rule is. I also called the DFA office in Manila and this is what we found out:

The current green passports can indeed be used until their validity dates but the risk is that by 2010, some countries have the prerogative not to accept the green passport as a valid travel document.

however, Take note that the International Civil Aviation Organization (ICAO) require all member states to issue machine readable passports no later than April 2010. This means that after April 2010, other countries can decide not to accept into their borders any foreigner who holds a passport that is not machine readable.

The DFA representative I talked to advised all Filipino passport holders to always inquire with the embassy or immigration office of the country they plan to go to about the validity of their non-machine-readable passports. The DFA cannot ensure that all countries will accept Filipino green passports after 2010. Some of them might but they also have the prerogative not to, according to the DFA.