It's unfortunate, especially with the large African American population in Pittsburgh, I'm suprised one of the lower rated stations didn't jump on the format opportunity.
Boston is somewhat understandable with the smaller African Amercian population than Pittsburgh, and at least we have 94.5 and 1090 in Boston, Pittsburgh has nothing! (right now at least, rumor has it some retired radio guy is opening up an urban station for Pittsburgh)
A friend of mine visited Pittsburgh a few weeks before the demise of WAMO and got some recordings of WAMO-FM, I've listened to them, it's sad to see another Hip Hop station bite the dust.
Some people say Urban radio is dying. I 100% disagree to the fullest. Urban radio as a whole is not dying, Hip-Hop is hitting rough times as of 2008, but other Urban formats like Gospel and R&B are still flourishing. Just remember, times trends and styles are constantly changing, Formats have their heydays and their comebacks. CHR is a great example, it's THE format right now with PPM, but it was facing an identity crisis throughout alot of the 90's, kindof like what is up with Hip-Hop now.