Bulgaria and Romania were originally also slated for entry in 2004, but this was postponed by nearly three years as it was apparent that they weren't ready. Romania, now is almost ready (officially, only technicalities remain), but Bulgaria is still quite far from being ready. The EU could have postponed Bulgaria's entry by one more year, but it has opted to include both countries at once and impose heavily restrictive terms instead.

Turkey was never going to enter before 2013 because of the necessity to make adjustments to the budget. But Croatia was semi-slated for entry in 2009, which will now probably have to wait a bit longer. The internal political reasons for wanting to slow down Turkish entry would still have been there as well and these exist in enough countries to form a blocking minority. The no to the Constitution has probably made the matter more urgent...