What is it and who needs one?
The ACR card is a microchip card that resembles a driving licence. It contains bio-metric data and can be updated automatically. It is a more efficient version of the old paper based system. The card contains personal information, a photo, your status and date of entry to the Philippines, visa type, fingerprints among other things.
This card serves as a re-entry permit, emigration clearance certificate and special return certificate. Once you have paid the correct fees for these the chip in the card will be updated accordingly. It does not replace your passport however, you still need a valid passport with your visa stamp to legally stay in the Philippines.
As of December 2009 tourists who extend their stay past 59 days have to obtain an ACR card as do students and employees with a pre-arranged employee visa. All registered foreigners and their dependents living in the Philippines with an immigrant visa are required to get an ACR card.
How to get an ACR I-card
If you live in Metro Manila ACR cards are issued at the main office of the Bureau of Immigration in Intramuros. Outside of the capital there are district offices located in major cities, a list can be found here.
If you are applying for the first time you will need to provide as much documentation proving your identity as possible. Your passport, birth certificate and driving licence are a good start. Once you have filled in the correct forms, waited in several lines and paid the fee ($50.00) you will receive your card within a couple of days (though it may take longer). They will issue you with an Alien Registration Summary which you take to your local immigration office within the first 60 days of each year to pay for the renewal of your card.
For more information check the ACR I-card section on the Bureau of Immigration website.