in reply to OT: Templating solutions - cross language rfc
Since you are looking for possible ideas, you may want to look into the TAL project created by the Zope team. It provides an unique alternative to the custom HTML tag solution.
Jean-Michel Hiver has ported TAL to Perl in the guise of Petal. There has been some some discussion on the list of porting it to other languages such as Java. From my limited testing, the TAL format cooperates well with GUI editors like Dreamweaver (unlike other template solutions such as Text::Template).
Good luck and please report back on what you eventually decide to use.