The release announcement at Enlightenment.org isn't too descriptive, but the news e-mail we received is, so it's included below.
These libraries were created after E16 to help with E17, the goal was to build infrastructure to aid development of rich graphical user interfaces that would be both fast and easy to use. They went through major rewrites over these past 10 years, but they have settled nicely over the past and now feel ready to be released. The libraries were quite stable, but by stamping 1.0 in them the developers are committing to API and ABI stability, encouraging them to be used abroad.
While the best known public user of such foundation libraries is the Enlightenment DR17, that is still unreleased, they are being used in other projects such as Canola, CarMan, BlueMaemo and is sponsored by various companies that use EFL in their products, such as Samsung, ProFUSION, Free.fr, Calaos and some that would like to remain unnamed.
After 1.0 final the work force will be put behind Enlightenment DR17 and Elementary, the widget set, with the goal to have everything 1.0 final before the end of the year.
Some related news that might be of interest is Enlightenment being used on the Ubuntu Netbook ARM port, an XBMC alternative using EFL, and Samsung sponsoring Enlightenment's development.