iPhone Calendar Colours
I use Google Apps for both me and a lot of my clients. Its great, and far better at iPhone sync than Apple's own Mobile Me service which is really flakey. This actually makes no difference to anything regarding the rest of this very short post, just thought I'd mention it!
When adding calendars to the iPhone, you don't get to choose what colour to assign to each one so you can end up with things like your work calendar being the same colour as your home calendar - and that's not a good thing in my book. You can get around this by adding calendars in a specific order so at least you can control which of the 6 set colours gets assigned to each one.
So for future reference, iPhone OS4 Calendar application uses the following colours, in this order:
Work no longer gets mixed in with home - on the iPhone at least :)