Carter was left in charge of the SGC while Landry and Mitchell were on vacation at Jack's cabin. Once Major Reynolds returned from a mission, he would assume command and Carter was going to go with Vala and Teal'c to join everyone at Jack's cabin. Needless to say, the super-scary alien monsters kept everyone from hanging out until the final reel.
What upsets me is that Carter is a Lt. Col. and Reynolds is a Major. There were tons of bird colonels at the SGC before Jack was promoted. You could site Carter's years of experience, including a year running SG-1 and several months running research at Area 51 as reasons why an O5 should be left in temporary command of the SGC. . . but not a Major. That's just idiotic (writing), in my opinion. As long as TPTB have been working with the Air Force to keep the show "authentic" it's amazing to me that they'd slip up like that.
There should be plenty of bird Colonels at the SGC. Realistically, there would be several layers of assistants to Landry that would take over day-to-day operations if he went on leave. They wouldn't leave something as imporatant as the SGC to an O5 Colonel and then a Major once she left.
Anyway, to those of you who thought that we are getting to keep all the nice technology and it's been replacing good teamwork, you'll be happy to know that we can't use the Sodan cloaks anymore.