In a new post to his blog today, Ken Guest talks about the split that's been made in a PEAR package for calculating the dates of holidays (Date_Holidays) for localization reasons.

We decided that this one package should be split into subpackages: one subpackage per region/country. Some advantages of this approach are that each driver / filter / subpackage gets it's own stability and version number - we wouldn't have to keep increasing the version number of Date_Holidays each time a new driver is added or when an existing driver gets a significant number of fixes.

To replace your current version of the package (with all of the regions built in) with a new version that still contains all versions, uninstall the Date_Holidays and grab the "Date_Holidays#all" package. Otherwise, you can check out the PEAR page for the main package and see the subpackage list if you only need one for your area.