This post will show you how to get your basecamp ical in google calendar (and onto your iphone, mac, etc)

• goto basecamp
• goto the main dashboard
• goto the bottom of the page
• copy the link for the iCalendar
• goto google calendar
• goto the bottom of the left hand bar
• goto the arrow next to ‘add’
• goto ‘add by url’
• paste in your copied link
• goto the start of the link
• change webcal:// to http://
• hit ok

It will take a couple of seconds to update, but you now have your basecamp calendar in your google calendar. Anything that gets added to basecamp will be automatically added to your google calendar – this is very useful for staying up-to-date with the tasks you have to perform.

please see this post for details on how to get your google calendar synced to your ical on your mac
please see this post for details on how to sync your iphone / ipod touch with google / gmail / google calendar / google contacts

Sources: HowToGeek