The LaTeX project is a small group of volunteers whose aim is to produce a major new document processing system based on the principles pioneered by Leslie Lamport in the current LaTeX. The new system is (provisionally) called LaTeX3; it will remain freely available and it will be fully documented at all levels.
The LaTeX team's first product (LaTeX2e) was delivered in 1994 (it's now properly called “LaTeX”, since no other version is current).
LaTeX2e was intended as a consolidation exercise, unifying several sub-variants of LaTeX while changing nothing whose change wasn't absolutely necessary. This has permitted the team to support a single version of LaTeX, in parallel with development of LaTeX3.
Some of the older discussion papers about directions for LaTeX3 are to be found on CTAN; other (published) articles are to be found on the project web site.
The projects code is all available on the project's GitHub site:
Release code from the team is also available on CTAN, most notably
Anyone may participate in discussions of the future of LaTeX through the
LaTeX-L; some development work (outside the project) is
discussed on the list. Subscribe to the list by sending a message
latex-l <your name> to listserv@urz.Uni-Heidelberg.de