I was provided a new blue Sky card when I was changed over from my old decoder to the current one (smaller black box).  At the time, the new blue Sky card was not recognised by Oscam, so I had to do a patch to get it recognised.  The difference was a simple card type code.  So clearly the old gold cards and the new blue ones are not compatible.  They both do use use the same Videoguard 2 encryption system though.

The new white boxes Sky is pushing so hard now do not use a card and use a different encryption system (Irdeto?).  Sky now broadcasts key streams for both Videoguard and Irdeto as separate streams on all muxes, so both encryption schemes work simultaneously.