[KSigkid]

Well, according to 26 U.S.C. Section 9038(b)(3):

"Amounts received by a candidate from the matching payment account may be retained for the liquidation of all obligations to pay qualified campaign expenses incurred for a period not exceeding 6 months after the end of the matching payment period. After all obligations have been liquidated, that portion of any unexpended balance remaining in the candidate’s accounts which bears the same ratio to the total unexpended balance as the total amount received from the matching payment account bears to the total of all deposits made into the candidate’s accounts shall be promptly repaid to the matching payment account."

(quoted directly from statute)

Now, Obama did not use matching funds...I think that his campaign would retain the funds for the next time he runs for office, and that if he didn't run for office, the money would go to the party. But, I can't find an exact cite for that, and I could very well be wrong (I'm not expert on campaign finance laws).