Regina crafted matrix of functions available in upcoming PostGIS 1.5. Currently, PostGIS 1.5 is available from trunk in the Subversion repository.
The PostGIS 1.5 documentation is available under the manual-svn node and here is the PostGIS Function Support Matrix.
Regina, great job!
By the way, there is an interesting problem with check marks. does anyone know how to define check marks based on Unicode and make them visible in IE8?