I was asked to do three interviews, the last of which involved creating an entire presentation for several hiring managers. Needless to say, it was a time consuming interview process that took several hours of preparation. After the interview, I was told they would let me know either way by the end of the week. I heard nothing, emailed them, and was told to wait another week. I never heard anything back after that. Unprofessional - after investing that much time in the interview process, the least I would expect would be a generic rejection email.