One of the great things about PHP isn’t the documentation, per se, but rather the centralized, searchable docs interface at PHP.net. Big thanks to Jeremy Durham for putting together an equivalent Rails resource site. There’s obviously still a good bit of work to do before docs are as complete and usable as they could be, but an online searchable repository like this is definitely a step in the right direction. Bookmark it, and add some example code and comments mang.
Oh and while we’re talking about documentation (or lack thereof), don’t forget to donate to the Rails API docs project at Caboo.se if you haven’t already.