This project was an incredible learning experience. There were many pieces that were built custom just for Sun/Oracle. I learned how to negotiate corporate america more through this project than ever before.
This project started as a port off of O'Reilly's custom CMS that they had built for Sun, and migration scripts that took all the data and merged it into Drupal nodes. We were building the site, including content types, taxonomies, fields, theme, etc. This included microsites for specific groups within Sun, and custom themes for each of these microsites.
When all was said and done, I bet we had 10-15 custom modules each handling specific pieces. We built a custom SSO solution. We built a server setup that included 3 web heads with a load balancer, 2 mysql servers that were in a master/master configuration. Memcache running on a couple of the web servers. Very scalable.
I think some of the things I learned here have to do more with office politics than any specific tech hurdle. We definitely covered some tech hurdles, but sometimes we had to do it the ugly way in order to keep the politics at bay. We came up with some really hacky fixes to problems because they had to do it a specific way.
Kenai.com came out as a forge, which replaced lots of the functionality of java.net, and a few years into it, we were integrating with kenai as a SSO provider, as well as making some of the links between projects link out to kenai instead of the resources we had built in Drupal. We did some API lookups before showing the links so that they wouldn't be dead links if they weren't there. This also handled any that were formatted differently than the default.
I may post edits onto this as I remember pieces. It was a really long project, and trying to nail down specific things I learned is tricky.
Update 1:
There was a JavaOne conference that was being released right when we were rolling out the updated java.net homepage, and I was able to go out and attend the conference and man the booth where we were telling people about the new site, and what it did, and why they should host their projects with us. Very fun. Very corporate. We got to go to the party they threw with the Eagles, Black Eyed Peas, and a bunch of other artists.