The first and only Ubuntu 14.04 development release can be downloaded from Softpedia
Canonical has just announced that Ubuntu 14.04 LTS (Trusty Tahr) Beta has been released and is now ready for testing.Canonical has stopped launching intermediary builds during the release cycle, with the single exception of a Beta version that is made available shortly before the official release. In this case, a little under a month.
This is the reason why you couldn’t find Ubuntu 14.04 LTS Alpha or Beta versions out there until now. The developers have said that a daily build that is upgraded constantly is much better suited to the way they push updates.
If you never tried a daily release of the latest Ubuntu OS, you'll certainly be surprised by the Ubuntu 14.04 LTS (Trusty Tahr) Beta, which gathers all the features and fixes that have been implemented in the last six months.
Let's start with the Linux kernel. Canonical will release Ubuntu 14.04 LTS with Linux kernel 3.13, which is now the most advanced kernel in existence. That will probably change the in course of the next week, but 3.13 remains a very good Linux kernel to have. As usual, the developers won't actually ship the official kernel, but their own version that is based on that branch.
Ubuntu 14.04 LTS (Trusty Tahr) Beta still makes use of Unity7 (to the disappointment of many users who have been waiting for Unity8), but there is also good news. The desktop environment has been updated a great deal and is now smoother and faster. The Scopes have received an overhaul, making them a lot more useful.
A number of smaller improvements were also made to Ubuntu 14.04 LTS. The developers have made some modifications to the window manager; users will now benefit from anti-aliased corners, and the 1-pixel border around the windows has been removed.
Another major update is the introduction of localized menus. Users will be able to switch from the applications menu in the top bar to menus integrated into the title bar of the active windows. This should prove very useful on monitors with high resolution.
Ubuntu 14.04 LTS Beta is still in development and, even if the developers are no longer integrating new features, they still need to take care of the bugs. It's possible to still find a few problems, so don't be quick to judge.
More details about the new Ubuntu 14.04 LTS Beta release can be found in the official announcement. Also, you can download Ubuntu 14.04 LTS Beta right now from Softpedia.