I got one of the new iTunes phones (Motorola Rokr) to check out. Bottom line is that it's a nice phone, but the music ability is very limited.
Good News
It mounts as a removable drive on a PC, so you can transfer files from Windows Explorer.
It plays MP3 files.
The sound of it is amazing for a small device. The built-in speakers sound bigger than they are.
As a package, it's small enough to fit easily in a pants pocket, but not as thin as the Razr.
It comes with 512MB of space on a removable mini-SD chip, but you have to open the case.
Bad News
It's limited to 100 files, even if you have disc space.
Even if you put a file on it, the phone doesn't see it. The only way that works right now is through iTunes, but even that isn't working right for me. It stopped after 28 files and iTunes was hung.
The "iTunes" music player is extremely basic. See photos below.
The camera is low rez.
We may be able to get MC working with it.
It's also been reported that MC11 works with the new iPod Nano.
http://yabb.jriver.com/interact/index.php?topic=29495.0