Facebook – Export (.ical) only Attending or Maybe Attending events from Facebook

There's an article on this here. I've not checked that it works, but it seems pretty straight forward. The essence is that instead of importing the calendar, you add the URL of your event feed as a public calendar - here's a summary of the steps:

1. In Facebook click on "Events"
2. Click on "Export Events" and copy the URL
3. In Google Calendar go to "Add" under "Other calendars" and choose "Add by URL"
4. Paste the URL you copied from Facebook and click "Add"

[Update: to make answer more complete]
If you run into issues with private events not showing properly then check out eventbusyfix.info. This site acts as an inbetween to clear the private flag and enable Gmail to show them properly (Thanks to prestomation for this tip)
[/Update]

Hope that helps!

I think the easiest approach would be to either e-mail the event to your Gmail account (as you suggest) or download the file from Facebook and then add it to Google from there.