If you hear it at the end of the interview process then it s a good indication that the employer is still looking for the best candidate, which means they aren't sure that if you fit in the bill or not. If you hear this that "we'll let you know next week (next month, etc.)" then it means trouble. And most likely if they are interested in your skills and ability, they'd lock you in for another round of interview. This is a common phrase used by lots of employers as they want to soften the blow of telling you that they don't you to be in this position.
