LiClipse is a set of plugins to enhance Eclipse and improve the overall Eclipse experience. It includes improved IDE theming, builtin editors for many languages (and a way to easily create new editors without delving into actual Java coding), usability improvements for all Eclipse editors, packaging of some common existing plugins and installers which are natively integrated into each platform.
LiClipse is a short for Lightweight Eclipse.
LiClipseText is the open source component that was born out of LiClipse which provides support for multiple languages.
See the LiClipseText About for more information.
No, LiClipse is not a fork of Eclipse (nor does it intend to be). Also, it should work well with existing plugins and can be installed in an existing Eclipse installation.
Now, having said that, it does have some overlap when it comes down to supported languages.
Usually, in Eclipse, you have to install a new plugin for each language you're working with, which does add more weight to an existing Eclipse installation, so, one of its targets is that you'll only need to install more advanced editor plugins if it's one of your main languages and you're really in need of its features as the more commom features such as syntax highlighting, outline, comment/uncomment and even basic code-completion can be provided through LiClipse adding very little weight to an Eclipse install.
The crowdfunding for LiClipse is now finished -- it can still be seen at: Indiegogo campaign page.