If you bank your 2010 points into 2011, they must be used by the end of the 2011 use year, or they will be lost. They cannot be banked again.
If you cannot use them during the 2011 use year, there is a provision that you may place them into the II system for a future "trade" reservation (time limits apply). I think this would have to be done within the first 8 months of your 2011 use year, due to the "rule of 4," which I don't completely understand, but which I believe is intended to "help" you lose your points.... (Sarcasm intended - I just haven't ever understood the rationale behind this rule!)