I believe that there are actually two options: (1) Rescue, and (B) RCI Deposit.
(1) "On or before December 31 of the current year, Members may 'rescue' any of their remaining ClubPoints from expiring by depositing their ClubPoints into the following year's account for reservations at Club Resorts..." (2009 Member's Guide, page 143) The fee for a "rescue" is $79 by phone or $69 online. (2009 Member's Guide, page 147).
(B) "Members may deposit current year ClubPoints or previously deposited ClubPoints into the RCI Exchange Program... RCI deposits are valid from the date of deposit through an an additional two calendar years." There appears to be no fee other than the RCI Exchange fee. (2009 Member's Guide, page 143)
Scenario: Before January 1st, I "deposited" my 2009 points to 2010, so in 2010, I could then deposit any leftover 2009 and 2010 points into RCI and they'd be good thru 2012. But if I had waited and "rescued" my 2009 points, they could not be used for RCI and would expire in 2010. Its one reason why, IMHO, its better to deposit than to rescue.