Limewire is a prerfectly legal file sharing programme. Now there might be one or two users who use it for uploading and downloading copyrighted material, and whilst Limewire expessly maintain that its application should not be used for such purposes, it is likeley that there are those who might break copyright laws and that might be, in some countries illegal.

If that doesn't answer your question do a search for copyright or something and you will find the subject has been discussed a few times