After 3 unofficial releases, Lubuntu was accepted to become a part of the Ubuntu family back at the Ubuntu Developer Summit in Budapest. It's still not 100% certain that Lubuntu will become an official Ubuntu flavor starting with version 11.10, but it's getting there, especially since you can finally download Lubuntu 11.10 daily builds starting today.
Julien Lavergne, the Lubuntu project leader:
After 2 years of work, and 3 "unofficial" releases (10.04, 10.10 and 11.04), we had recently an official go from the Technical Board and ISO images are now made like other Ubuntu flavors. I hope the 11.10 will be the 1st official release of Lubuntu as a member of the Ubuntu family.
Lubuntu uses the LXDE desktop environment and among the default applications are: Chromium browser, Openbox window manager, Pcmanfm file manager, Abiword and Gnumeric for office work, Pidgin IM, Audacious music player, Gnome-mplayer and of course, most of the LXDE components.
Download the latest Lubuntu 11.10 Oneiric Ocelot daily ISO @ http://cdimage.ubuntu.com/lubuntu/daily-live/current/
Note: selecting "Try Lubuntu" fails with today's daily ISO, but selecting "Install Lubuntu" should work (see this comment if you have trouble logging in).