Apparently, the pension board offers the option of paying a full amount now, or making a partial payment now and another later. Of course, the other payment is larger, to make up for the lost investment income. I think that the interim village manager and the non RCA board members voted to make the full payment now.
You are right that the pension payments are guaranteed. No matter how the funds are invested - the municipalities have to make up any investment loss. That is one of the differences between goverment plans and those available in private industry - who converted to cash balance plans over the last 15 years. Also, private pension plans do not have COLAs, but goverment plans do. We are now in the absurd situation where there will not be a Social Security COLA on 2010, but many goverment plans are guaranteeing 3%. I don't know if that is the case with the municipal employee plans, but it certainly is the case with teachers and state legislators.
I would have funded the full pension liability. I don't believe in fooling myself that deferring obligations is some sort of a savings.