The proposal page shows Ubuntu in a mix of states ("Public beta"/"Public beta begins soon!").
The site, however, has fully launched, becoming the first Area51 site with its own real domain. Congratulations!
Good catch. This is fixed now.
The slightly early launch of Ask Ubuntu to coincide with the release of Ubuntu 10.10 has made this happen. No doubt it will be fixed soon! (But meanwhile I don't suppose Area 51 is the main way new visitors will be finding us...)