Ubuntu Jaunty reached end of support life last October and apparently packages have been removed from Launchpad PPAs too.
Given that it is impossible for me to build binary packages for Jaunty in the Wt PPA due to missing packages, the Wt PPA will no longer provide new packages for Ubuntu Jaunty. The last stable version of Wt for Jaunty is 3.1.6.
On April 2011, Karmic reaches end of support, and Hardy reaches end of support for desktop (support for servers will be available until April 2013). I will provide Wt packages for those distributions while Launchpad supports them.
Packages for 3.1.7a are already available for Ubuntu Maverick, Lucid and Karmic, as usual. Packages for Debian Lenny (in the Wt OBS repository) and Ubuntu Hardy packages will be ready in a few hours. Source packages for Debian Sid are available from mentors.