Lack of courtesy in keeping job seekers informed has unfortunately become the norm in the US the last 5-10 years.  They claim its because there are just to many applicants for each job posting to respond to each applicant but I think that's a lot of baloney.  If you call someone for an interview and give them a timeline for decisions, it is very unprofessional not to MAKE the time to keep them advised - especially if they are not chosen for the next round or the position.

I would call to verify your status so you can "cross them off the list" if you weren't chosen.  There was a position I applied to last month and when I didn't receive a call for an interview within two weeks of the closing date, I called asked if they had chosen their candidates yet so I could remove the job from my list if they had.  

Michelle