I think I am with Dries that a language web editing front end is probably the most important thing right now. Adding a new language could be a SQL dump and module. The main function of the module could just be to add it's language to the various language selection menus.
One useful thing could be to get this language web editor working on Drupal.org, so various people can collaborate to create the translations. It may be usefull to have some kind on 'notes' feature, where translators can add notes about a particular change (e.g. I changed 'ty' to 'uchaf' as this link takes users up a level, rather than to home).
This is all possible with CVS, but of course CVS is not easy enough for quite some folks. You get commit messages exactly as you described, plus you have version control, which is already proven. Using simple text files (PO files) the diffs are even easier to read then those XML files, you reindent, and all the lines suddenly changed. It is unfortunate, that CVS is not easy for quite some people, but IMHO it does not mean we should create a whole new system. The Tortoise tools for Windows are quite good in simlifying CVS/SVN.
If any import/export of translations is worked on I would suggest a XLIFF [1] standards based XML format would be better than: * a 'roll your own' XML format: as XLIFF translation tools are already available. * PO files: as XML has, I think, better facilities for full description of international character sets.
Not that we have no need to deal with international charsets, as we only support utf8, nothing else. PO editors do utf8 well. Let us know the advantages of switching formats, switching desktop tools, writing new import/export code along your suggestion please. What is not possible now? What is going to be better? Goba