From the Department of State website:
Important Notice: Effective February 1st, 2010, when both the I-129F petition for a nonimmigrant K visa and the I-130 petition for an IR-1 (or CR-1) spouse of a U.S. citizen visa have been approved by USCIS and sent to the National Visa Center (NVC), the availability as well as the need for a nonimmigrant K-3 visa ends. If the NVC receives both petitions:
•The nonimmigrant K visa will be administratively closed
http://travel.state.gov/visa/immigrants/types/types_2993.html#4
Important Notice: Effective February 1st, 2010, when both the I-129F petition for a nonimmigrant K visa and the I-130 petition for an IR-1 (or CR-1) spouse of a U.S. citizen visa have been approved by USCIS and sent to the National Visa Center (NVC), the availability as well as the need for a nonimmigrant K-3 visa ends. If the NVC receives both petitions:
•The nonimmigrant K visa will be administratively closed
http://travel.state.gov/visa/immigrants/types/types_2993.html#4