I was on SW FLT 2623 last night into San Diego. FIrst, they had us circle around for awhile due to low visblitlty. Then, we were finally cleared to land 30 minutes late. At about 10 ft from touchdown, the Captain gave it full power and we shot back up into the air very quickly! After about 5 minutes, he came on the intercom and told us that another plane had been cleared to be on the runway and was in path. I don't know how close it was, but I do know we were very close to the ground!