Checking in texinfo sources I don't know what sources you're looking at. po/it.po does indeed exist in current Texinfo CVS.
(more than a year ago).
The last official Texinfo release was (unfortunately) in September 2008.
Evidently it.po came in after that. I don't know when the next release
will be. As soon as possible, but no sooner.
Best,
Karl
