Croatia, Haiti and Serbia joined the Hague Adoption Convention in December 2013. It will come into effect in all three countries on April 1, 2014, bringing the number of Contracting States to 93. The Hague Conference announcement is available here.
The US State Department is currently assessing whether it will be able to certify Convention adoptions from Haiti after March 31; see this statement posted on January 16. There has been no similar notice posted to date for either Serbia or Croatia.