Honest question from a maybe-future Android dev: is it notably more challenging to develop for Android during periods when the source is not yet public? For example, is a lot of platform doc written from the POV of someone who expects you'll just peep the code when questions arise?
Update: +1 to everyone thinking 'man, I bitch about google sometimes, but this kind of thing is totally legit and awesome'
I do Android dev full time and it's pretty rare to actually need to look at the source. The only time is when encountering a strange bug that you suspect is caused by the underlying implementation.
Google has generally been good about releasing emulator images prior to releases, though usually it's only a few weeks. Luckily, it takes time for Android versions to achieve large market share, so any bugs can be squashed before it's a big problem.
Sometimes when I'm in a bad mood, the API and online doc are not cutting it - I start wondering why it doesn't work the way I'd expect it to, and from there I have multiple options, from StackOverflow to Google Groups to ordering a book on Amazon.com, and this is the true productivity killer because of, you know, the internet.
The definitive and fastest answer will always come from reading and understanding the source code, as I don't have to hope that someone had the same problem I'm having and someone else had an answer, or that someone will reply to my question before I give up. Eclair, Froyo and Gingerbread sources were enough for 99% of my needs though, but there was always this shadow of doubt for Honeycomb-specific features...
For the most part, having the latest source readily available will greatly reduce the amount of open browser tabs, and for that I'm thankful :)
Update: +1 to everyone thinking 'man, I bitch about google sometimes, but this kind of thing is totally legit and awesome'