As Jani Monoses stated in an email:

There are less and less chances of getting bugs fixed with the release
closing so if we want to avpoiod the usual post release surge of reports
please test the daily images.

A new thing worth checking out in the latest is passing the
only-ubiquity parameter to the kernel (use F6 in the boot menu)
It will only launch ubiquity no the whole desktop. It was introduced to
enable Ubuntu installs on 256M machines, but I am sure it now helps
Xubuntu Live with its mem requirements. So please check it out it may
even run in 128M but should definitely no longer need 256 as it does
now.

In order to prevent a sudden surge of bug reports after Xubuntu 7.10 (Gutsy Gibbon) has been released, everybody is encouraged to test the new daily images of Xubuntu which you can find at the Xubuntu Gutsy Daily Build download page, using the testing instructions, and to report bugs using Launchpad.

Please note that daily builds are generally unsuitable for normal usage and that bugs will be present.