While Ubuntu itself no longer does alpha releases, several of its derivatives are doing their "Saucy Salamander" Alpha 2 releases today.
Kubuntu, Lubuntu, Ubuntu GNOME, Ubuntu Kylin, and Xubuntu are up to their 13.10 Alpha 2 state today. Ubuntu isn't doing alpha releases as they recommend just using their latest daily LiveCDs at the time of testing, which they try to maintain in an always-working and good state.
The new alpha releases for these Ubuntu family members mostly incorporate package updates but there's also other changes like Lubuntu now supporting ZRam for use on systems with low RAM capacities, replacing Firefox with Chromium as the default browser, etc.
Downloads are available for Kubuntu
, Ubuntu GNOME
, and Ubuntu Kylin
. Of course, all of these derivatives plus Ubuntu 13.10 itself will be released as stable in October.