Recess appointments, which a president can make when Congress is not in session, are temporary and generally last to the end of the year.
Recess appointments 1) are temporary: they last until the end of the current Congress (i.e., until Jan 4-5-6 next year), and 2) serve unpaid.
The appointments are good until the end of the current Senate (two year) Session. Those sessions last two years, so a recess appointment could last almost two years. Current recess appointments will expire with this Congress, at the end of the year.
http://www.senate.gov/CRSReports/crs-publish.cfm?pid=%270DP%2BP\W%3B%20P%20%20%0A
Recess appointments are good until end of current Congress, Jan 2011.