According to ubuntu 10.04 schedule, it was released yesterday, but Steve Langasek announced that it will be delayed one more day to Friday March 19 ,
Owing to some late image rebuilds for a couple of critical issues that we
didn't want to leave our beta users subjected to, validation of 10.04 Beta 1
is still in progress. This means that Beta 1 will not be released on
Thursday, March 18 as planned; it will be released tomorrow, March 19.
To help us release the beta with confidence tomorrow, please consider
participating in the ISO testing today, as described at
Also, as you're going through ISO tests, please also help us fill in the
blanks on <https://wiki.ubuntu.com/Testing/Plymouth> so we can complete our
understanding of the remaining boot-time issues affecting Beta 1 and make
Beta 2 truly spectacular!
On behalf of the Ubuntu release team
Fixed a lot of bugs since alpha 3 version, improved nvidia graphics driver, ubuntu one syncing, new themes, we reviewed in ubuntu fresh look.
Will review it as soon I done download it.
also you can Download ubuntu 10.04 beta 1 from here
And more information, mirrors Here