Visited the Bass Rock 17th August 09.  Fantastic.  Contact the Scottish Seabird Centre (http://www.seabird.org/home.asp) if you fancy a visit.  It's expensive (£95) but worth every penny.  This is something I have ALWAYS wanted to do, and now at the age of 67 I've done it at last!  The white colour on the Rock is wall to wall gannets.