Android - How do I send a contact via SMS?

Surprisingly, you need a third party app.

http://www.appbrain.com/app/shareContacts.NS.com

For users with Ice Cream Sandwich:

Using the stock messaging app, you can attach contacts to the message either on "Text" or "vCard" formats.

When writing the message:

1. Touch the device "menu";
2. Touch "Attach";
3. Touch "Contact";
4. Touch the desired method.
   You will then be presented with your contacts list to select the desired contact.

^{Screenshots taken from LG-P700 running Android v4.0.3.}

On HTC Desire HD (Froyo) whilst composing an SMS: Menu > Attach > Contact(vCard)

Or is that a HTC Sense feature?