Soemthing is definitely up on this front. I have a MacBook Pro with Snow Leopard, Mountain Lion and Mavericks on it and I keep three different iTunes in each OS for testing - my preference is to iTunes 10.6.3 and Snow Leopard, and several weeks ago, the radio stations tuner went offline. Oddly enough, I'd saved the list of stations I use often and didn't really miss it - these interruptions happen often enough but are usually temporary - until one day I wanted to change up my stations selection and uhhh, nope. still offline.
Hmmm.
Not even in iTunes 11.1.1.. so I took the update to 11.1.5 on the Mavericks install and also on my main machine - the MacPro at home with Snow Leopard on it.. again, I upped that to 11.1.3 and no dice *until* I took the last update (which I really, really HATE the UI and how the window minimizes and the whole icons/album art - that is just *so* much rubbish, unnecessary 'bells and whistles' for the ADD afflicted twenty-somethings who are coding for Apple now.. Come on kids.. for real?) and I've radio stations coming in on the internet tuner in 11.1.5.
I'm somewhat ticked by Apple over this, as I have several PPC Macs I use on a fairly regular basis and enjoyed being able to get the radio station lists. At this time, since I have the option to run PPC code in Snow Leopard with the Rosetta installed, I'm running the old-as-grit Songbird 1.10.0a for PPC - http://www.the-eleven.com/tlegg/blog/2011/05/24/songbird-osx-ppc-1100a/ - and it's got the Shoutcast tuner XPI file handy so that is what I'm going with for streaming internet. (You load the add-on like you'd do in Firefox, the folder with the working .xpi files is included in the .dmg) Ironic that the Shoutcast is giving me nearly double the returns per music genre as what the updated iTunes is - and Shoutcast *itself* is in a transition as the service got bought by a firm called Radionomy and it's all messed up as they transition to new servers - but they're running circles around what Apple is offering right now.
If you can't run the Songbird, try Nightingale, http://getnightingale.com/ they *might* have the Shoutcast stream modules running already. I was there a few nights ago and it was all still in transition..
Good luck!