Actually the MOD Internet policy accepts that the provision of DII meant that many MOD staff - both service and civilian may want to use the Internet. It further accepts that 'surfing the net' provides the ability to increase IT awareness and skills.
A DIN was issued sometime ago which basically said that MOD personnel could use their IGS account for 'personal surfing' for up to 15/20 minutes during the working day. Staff that chose to do this would be expected to work the equivalent extra time prior to leaving though. Banning access to Ebay seems to go against the spirit of this DIN.
I doubt the service websites will be banned - the ensuing media frenzy would be enough to lift it if it happened. After all bearing in mind how many stories journos get here, they may have to do some work and write their own story if we couldnt post.