But Seriously...

How to Update Facebook From Google+ (Without Using an Extension)

Facebook provides each user with a unique email that they can use to update their Facebook with. This way you can email a status update, picture, etc. without needing to access the site or the app, plus it works with any email address.

We can use that email address to cross post from Google+, here are the steps to configure it:

Login to your Facebook account and head to http://www.facebook.com/mobile/. In the middle of the page there will be an email address that starts with some random characters followed by “@m.facebook.com”. Copy it.
Go to your Google+ Circles page. Create a new circle (I just called mine “Facebook”) and add the email address that you just copied as the only person in the circle.
Now just post as you normally would but include your new circle in the post and check the boxes to notify by email.

Facebook takes a couple minutes to update but it does work, I’ve tested it a few times. It should also work from any browser and the mobile app (although I haven’t tested it yet).Try it out.

Update: You can probably use the same method to update Twitter as well with one of the many websites that offer tweet by email, but I’m not so comfortable using those services because they are third party.

Update 2: Unfortunately it looks like your text will cut off after about 50 characters using this method. This is because Facebook uses the subject of the email as the status and Google+ truncates the subject text in the notification email. Right now I don’t think there is a way around this but I suggest that you use Google+’s “Send Feedback” function and request more subject text in the notification emails. Who knows, maybe they will consider changing it.

Update 3: Now that Google+ has had some time to grow, I found that this extension is probably the best method of cross posting. Seriously, it rules.