While Ubuntu Linux no longer participates in alpha releases, other members of the Ubuntu family did their first 13.10 "Saucy Salamander" alpha releases today. Coming out today in 13.10 Alpha 1 form is Kubuntu, Lubuntu, Ubuntu GNOME, and Ubuntu Kylin.
Canonical's Kate Stewart announced the first Saucy Salamander alpha release moments ago. ISO images are available at the moment for Kubuntu, Lubuntu, Ubuntu GNOME, and Ubuntu Kylin. Ubuntu itself doesn't do alpha releases these days since they pride themselves on daily usable quality and you can easily fetch the latest daily ISOs of Ubuntu 13.10 "Saucy", along with daily ISOs of other flavors like Xubuntu.
For the Ubuntu derivatives doing an alpha release today, you can read more on the mailing list