Portage currently has no functionality to support installing nightly builds of software. This makes sense, as things can change between builds to invalidate the ebuild file, but certain pieces of software (such as Freenet, see bug 3919) are highly self-contained and could benefit greatly from this. Basically, what it comes down to is a need to be able to bypass the md5sum verification of the downloaded files. With this in place, the latest .tgz or .jar could be downloaded and installed without having a new ebuild released every 24 hours.
tuxisau's comment in bug # 3919 seems well enough, in my opinion, without having to resort to the measures you request.
Which comment, specifically, are you referring to? I understand that having md5sums is necessary to ensure a file downloaded properly, but many formats (such as both .gz and .jar) have internal checksumming capabilities. Perhaps an overridable (such as src_unpack) could be used to validate downloaded files without relying on and md5sum. (Then again, the digest file is also used to make sure a file downloaded completely... hmm...)
"I think it's a bad idea. The old ebuild can be a reference to be used for newer versions. By the way, I did install it yesterday, and then ran "update-freenet" script, and it downloaded the latest version, that worked perfectly." ^^^^ that one
