Goplan provides RSS feeds for those who like to subscribe to project activity in their favorite application or service (apps like Reeder, Netnewswire, Feeddemon or sites like Google Reader are great places to look). Whenever you see an RSS icon on Goplan, right-click it and copy the link - then paste and subscribe to it from your favorite application.
A note on RSS feed security
Your RSS feed for project and company activity on Goplan should be kept private - each member of a company has his own unique RSS feed address, so don't share these around your organization unless you know what you're doing. If you feel your feed may have been compromised, you may reset it from your Preferences screen - this will invalidate your old RSS feed addresses and will force you to subscribe to them again.