iPhone 3.0 features Calendar Subscriptions, where you can enter the URL for a shared calendar and near-instantly add it to your iPhone.
That's all well and good to share a family or business calendar, but what about more wide-ranging ones? What about national holidays, religious events, movie release dates, sports team schedules? Luckily, Apple's already made this simple for Mac OS X iCal users, and even more luckily it works just as simply for iPhone 3.0 users as well.
We'll share how, after the break...
Adding Subscription Calendars
Just point Mobile Safari on your iPhone to: http://www.apple.com/downloads/macosx/calendars/. Apple provides categories for Most Recent, Most Popular, Alphabetical, Staff Picks, plus a handy search box. Once you find a calendar that interests you, click the Download link.
Your iPhone will ask if you want to subscribe (see image above), and once you confirm, will offer to take you straight to your calendar events to see what's new.
Viewing Subscribed Calendars
Each subscription is given its own calendar in the iPhone Calendar App, so you can choose just that calendar to view. All views, month, day, and details are supported.
Removing Subscribed Calendars
Not all shared calendars are created -- or maintained -- equally. Movie Release Dates doesn't seem to include June or July yet (making it rather useless at the moment), though national holidays and others seem quite up to date.
If you subscribe to a calendar that later disappoints, just head on over to Settings > Mail, Contacts, Calendar. You'll see all your subscriptions listed under Accounts. Choose the one you want to edit or remove, and hit Delete Account if it displeases you.