iTunes the program? Or iTunes media? (songs, videos etc).
If the program, no - at least not to be useable.
For media, it'll largely depend on the MP3 in question - whether it has support/drivers for Mac, and whether it requires it's own software to migrate. Many basic MP3 players utilize a 'drag and drop' method of loading media onto it, so I wouldn't image it to be a huge problem. If it's an older Sony MP3 player, you may hvae issues as they have proprietary software & strange authentication.