Many Ubuntu-based distributions are doing their 14.04 "Trusty Tahr" Alpha 1 release today, except for Ubuntu 14.04 LTS Alpha 1 itself.
Available today in 14.04 Alpha 1 form is Edubuntu, Kubuntu, Ubuntu GNOME, UbuntuKylin, and Xubuntu. Canonical isn't putting out a 14.04 Alpha 1 of Ubuntu because -- as with recent release cycles -- they encourage daily testing of Ubuntu 14.04 and try to make sure the daily ISOs are always release-ready. So simply grab the latest Ubuntu 14.04 daily ISOs whenever you want.
The 14.04 Alpha 1 updates in the released distribution updates today mostly come down to updated packages and other "Trusty Tahr" changes pulled in from the Ubuntu 14.04 archive.
More details on the Trusty Alpha 1 releases can be found via this mailing list release announcement
. The official 14.04 release is due out in April while an alpha 2 will come in late January and the first beta in late February.