Not even 10 minutes after I reported that Notch and the development team were planning to release a pre-release update today, developer Jens Bergensten actually released the official Minecraft Update 1.9 version 6 pre-release.
Jens did confirm that the prerelease "is another prerelease and not a release candidate, but we're getting closer."
Notch actually announced earlier that the release candidate is planned for Sunday, so expect another update then. While the pre-release update version 6 will most likely be aimed at fixing the bugs from previous 1.9 updates (listed here), Notch did remind us of a few things left to do.
"The new sounds, fixing bugs from this prerelease, some minor polishing. And we'll do that on sunday," added Notch.
The update on Sunday should be the final release we'll see before the official "full" version of Minecraft launches next week at Minecon.
Be sure to "help test the ender fight in multiplayer as much as possible" and let us know what else you find.
xthth