Mine has the same notation: "Valido [sic] hasta la expiracion del pasaporte." (The "V" is cut off at the edge, but I'm sure that's what they meant, "valid"). Translates as, "Valid until the expiration of the passport."
According to the Chilean Embassy website, the fee is $140 (says $131 on the main page, but it's updated elsewhere on the site), and I just now checked both the English and Spanish language versions to confirm that it is indeed still good for the life of your passport. I got mine in February 2008 and returned in September 2008 and that's the way it worked back then as well.
That's excellent advice about how to proceed through the entry process in the Santiago airport. You must go to the booth on the left, not the long lines on the right, to pay this "reciprocity fee" as you first enter the passport-checking area. I and most of my fellow OAT travelers (whom I had not yet met) didn't know that when we entered (OAT's representatives are not allowed into this area and must greet you farther along when you've cleared customs, reclaimed your luggage, and exited) and we just naturally followed the crowd to passport control, waited quite a while to get to the head of the lines, only to be redirected back to pay the fee, then start the queuing process all over again.
If and when you return to Chile the next time on the same passport, you can skip that step and go right into the queue. When you have your little reciprocity fee receipt, staple it in the back of your passport in case you ever re-enter so you won't have to repay. Worked for me when I returned eight months later -- straight to the passport control line, they found the old receipt stapled into the back page, and put me right on through.