According to the latest fare/flights load at CO res, CO will be operating its 737-900's between IAH-CZM (eff. Jun 14) and IAH-PVR (eff. Jun 24)

IAH-CZM
14Jun01 CO 1209 Departs IAH 0924 Arrives CZM 1134
14Jun01 CO 1204 Departs CZM 1245 Arrives IAH 1434

IAH-PVR
24Jun01 CO 1741 Departs IAH 1150 Arrives PVR 1423
24Jun01 CO 1740 Departs PVR 1520 Arrives IAH 1744

Thus far, these are the only 739 origins/destinations I've seen, however I'm sure as the CO route planners continue to 'tweak' the schedule, we'll see these 739's to other destinations, possibly EWR-TPA, MCO, FLL.

Peace
COexERJ