Can I send my location in an imessage directly from the messages app?
Edit: Sorry, I skimmed a bit and missed that you figured this part out already. I don't believe it can be done directly from the Messages app. In conceptual terms, the iOS model for data sharing is typically such that you send data from an app, but the "sending apps" generally can't grab data from elsewhere. This is true for most things except photos, i.e. you can send a contact from the Contacts app, but you can't directly attach one from the Messages app.



Original post:

You can do this by tapping the blue arrow (blue i on an iPad) on any location (dropped pin, current location), and tapping Share Location. It will give you the option of sending via email, Message or Tweet. Your recipient will get sent a contact with a maps url and address.