Mark is a lead developer at Wordpress, I'm liveblogging his session on Advanced Wordpress. And he just jumps right in. So here we go.

Scaling. 
Best option is WP Super Cache. Sits in between WP and the clients and cachles the HTML Output WP produces. Works with any level of hosting or traffic. Can fine tune settings to exlude some pages if they have to be dynamic. Obviously we could have a whole hands on class just for this.

Other option is PHP Opcode Cache, APC, eAccelerator, XCache. Try them and see which one works. If you have your own server MySQL Query Cache can speed things up. Batcache is your blog is so popular it requires more than one server. Oh to have that problem.

Upgrading with Subversion
Mark recommends not using FTP to update WP anymore. Instead use Subversion. It's a way to track code changes. Everyone should use because it is less error prone. Will also work with plugins.

address starts with http://svn.automattic.com/wordpress/ [ file url ]
branches/2.6 - recommend to just get latest files for latest version
tags/2.6.2

cp -R wordpress wp-backup
cd wordpress
svn export -force url . [ the space before the period is important ]

Don't forget to visit WP admin to check for changes.

this will update in just a few seconds. Advice from the back: search :SVN Red Bean" for online book tutorial.

Hardcore: keep all your code in Subversion. Again... over my head.


Advanced URLs techniques
You can add
/feed (or /atom, /rss2) to get feed of anything
/?paged=2 add that to any feed to get 11-20 of feed
/?cat=3,-4 to view just by category or exclude category from feed.

Now you can use this to offer customize feeds to people who come to your site just for one feed.

/?s=foo (? has to be at the end after feed if you're searching a feed)
/search/foo
/search/foo/rss2 - lets you specify the feed
/search/foo/atom
/author/john/feed/ let's you specifiy author


Post Loop - WP_Query

WP_Query let's you customize the loop. Actual code up on powerpoint. Too much to type. Alas.