The Hague Conference on Private International Law reports that the Hague Convention of 13 January 2000 on the International Protection of Adults will enter into force on January 1st, 2009.
This is because a third country, France, has ratified the Convention on September 18th, 2008. There are thus three countries which ratified the Convention: France, Germany in 2007 and the U.K., but for Scotland only, in 2003. Pursuant to article 57 of the Convention, this is what was necessary to trigger the entry into force in those states on the first day of the third month after the third ratification.
On the same date, the Convention was also signed by five new states: Finland, Greece, Poland, Ireland and Luxembourg.
There are now ten signatories altogether. They may eventually all ratify the Convention. If they do not, will someone assess the efficiency of the whole enterprise? This is a lot of transaction costs for harmonizing the law of three states only.
UPDATE: for a discussion of whether the Convention applies in England and Wales irrespective of the fact that the UK only ratified the Convention for Scotland, see below the comments of Michelle S. de Bruin.