Ask HN: Unique Developer Blogs?

I love a very specific kind of blog/article/post and I'd love to know if more exist. They post 'lessons-learned' and 'process-insight' articles about their large scale development efforts.

Specifically: These are not "how-to" copy/paste script sites, they don't offer a downloadable library at the end, and they are run by legitimate, innovative, startup-like companies. The ideal posts are higher level views of "How did we solve this problem?", where "problem" == something relatively unique and interesting, not "How do I do AJAX in jQuery?".

Examples: - http://codeascraft.etsy.com/ - http://engineering.twitter.com/ - http://bigbucketsoftware.com/2010/04/02/checkpoints/ - http://sudokugrab.blogspot.com/2009/07/how-does-it-all-work.html

Any and all favorites would be welcome.