I use gmail via exchange and get all the calendars I've got set up. Here are the steps:
Originally Posted by iquinn
First, set up via exchange. Then--this is the important part--you need to tell Google which calendars to sync. Here are the instructions:
Mail, Calendar, & Contacts: Choosing Which Calendars to Sync
Google Sync allows you to choose up to 25 Calendars with the Calendar app on your Apple device.
To select which calendars to sync to your Apple device, follow the steps below:
1. Open the Safari browser on your device and go to http://m.google.com/sync.
2. Sign in with your account and select your device from the list of devices you've set up for Google Sync.
3. Follow the prompts from there.
(If you use Google Apps, follow these steps)
1. Open the Safari browser on your phone and go to Google Mobile
2. Click on Google Apps user? at the bottom of the screen.
3. Enter your domain name (e.g., YourDomain.com).
4. Click the Sync icon in your domain area (this section has a green background).
5. Sign in if required.
6. Select your device to configure Calendars.
It's all worked for me since setup, without the need for any awkward workarounds or third-party apps.