They will be supported for five years on desktop and server
The Ubuntu Technical Board decided yesterday, January 9th, to make the upcoming Xubuntu 12.04, Kubuntu 12.04 and Edubuntu 12.04 operating system, LTS releases.Therefore, Xubuntu 12.04 LTS, Kubuntu 12.04 LTS and Edubuntu 12.04 LTS will be supported for five years for both desktops and servers.
This is no surprise, as in mid November 2011 we've announced the highlights of the upcoming Precise Pangolin releases, were we've stated that Kubuntu and Edubuntu will try to become LTS (Long Term Support) too.
Kubuntu was already an LTS release, but now it will also be supported for five years, just like the Ubuntu 12.04 LTS release.
Ubuntu 12.04 LTS (Precise Pangolin) will be released this spring, at the end of April. Long-Term Support releases of Ubuntu are pushed by Canonical every two years.