Apple's MobileMe News shares how to view calendars published to MobileMe on iPhone:
MobileMe members who use iCal on a Mac can publish calendars to MobileMe to share with friends and family. To publish an iCal calendar, simply click the calendar and select Publish from the Calendar menu. You can then send an email inviting other iCal users to subscribe.
Your friends and family can now subscribe to your published calendars and view them on their iPhone or iPod touch running iPhone OS 3.0. They simply view the invitation email on their device and tap the link to set up the subscription to the calendar. For more details on how to publish calendars to MobileMe and subscribe to them, please read this support article.
Subscribing to calendars is a great new feature in iPhone 3.0, but is buried in the Settings. This, however, looks like a much friendlier way to set them up. Hopefully commonly shared calendars, like holidays, sports team schedules, etc. will set up some similarly easy add options for iPhone users.