What is the easiest way I can send one contact's phone number to another on my Android? I have to send two contacts in my phone book to another contact, on my Nexus One Android 2.2. How can I do this easiest?

On my old SonyEricsson this function was on a nearby menu, but I can't find it on Android.

I have also tried to copy the phone number when in edit mode of the contacts, but I can not paste it when composing the SMS to my contact. Is there really no way to transfer a contact via SMS or MMS on Android other than writing the numbers down on paper and then write them in the SMS message later as in the stone age?
Copy and paste from Contacts app to Messaging app should just work without any problem, I've used it a few times before to copy lines from addresses, emails and that sort of thing into an SMS.

Are you sure you long-pressed long enough in the SMS message to get the input menu up with the Paste option on it? Or that you copied it properly in the first place? Copying data from a Contact is most easily done by Editing the Contact, then long-pressing on the field you're interested until the input menu comes up with the Copy All option.