Many of you have been asking this question in our comments. Here's what we know:
Back in April we linked to a story from Fashion Week Daily which said that "Michael Kors will not be available for the first four tapings of the third season of Project Runway due to prior commitments to production on his clothing line..."
Just before filming began in May, Women's Wear Daily mentioned in an article about Vera Wang that "The designer will have an even wider audience when she fills in for Kors for a few episodes of "Project Runway."
Based on this earlier news, we were surprised to see Michael Kors present for the first runway judging. The production schedule must have been adjusted to accommodate him. Our best guess is that he will be out for at least the next two episodes as well, with Vera Wang filling his shoes until his return.
ETA: According to Andy Cohen, Michael will return on August 9 for Episode 5. Thanks Andy!