You can resolve this by the following steps:
From the home screen press the menu key> then press settings> then press accounts> then press on your facebook account> uncheck sync contacts.
Please repost if this does not help.
I have the same problem with all my FB contacts appearing in my Contact List & when I followed the instructions SammuelP gave above I also ended up with the only option being "Remove Account"
Just REMOVE the Account ... You don't need that Account there if you don't wish your FB contacts interspersed with your other phone contacts ... and removing it does NOT effect the usage of FaceBook APP.