No, LimeWire does not have an internal audio player like Napster has (or had, depending on how you look at it). If you want to hear music from your library without having to open an explorer shell/Finder Window/whatever then you can select the song you want to listen to and click "Launch." This will launch your default audio player and play the song. LW for some other OS's, such as Mac OS, may not work very well all the time, but the Windows version (1.4 +) all work fine.

Have fun with LimeWire!