I'll let someone else fill in the details of portals. AFAIK, dotLRN 1.0 should be installed on 4.6, not on HEAD. dotLRN 1.1 will use 4.7 (when it's released) with all the i18n code.
new-portal is on HEAD, but the information I have is that OpenForce is not done with the refactoring it's doing on the package (so it's new-new-portal).
The main page on openacs.org is done with ETP (Edit This Page) for the middle content. The other boxes around it are done with <include> templates.
You can checkout the source code for openacs.org from CVS, the module is called openacs.org-dev. Look under the www/templates/ directory.
-Roberto
