Can I send an iMessage to a iPad user from my iPhone?

I'm amazed I can't figure this out - my friend has an iPad running iOS5. He can send me an iMessage to my phone using my AppleID. But (outside of replying to his message) there is no way for me to send him a message using the Message app, since it only lets me enter phone numbers.

So, how does an iPhone user send an iMessage to an iPad user's AppleID?

EDIT: Does this work for anyone else? ON AN IPHONE (3GS, if it matters, running iOS 5), open Messages. Hit the 'Compose' button. Try to type in an email address in the 'To' field.

There is NO WAY to enter an email address there, afaict

How does an iPhone send iMessages to iPad:

1. Make sure iMessage is set "on" on both devices
2. On your iPhone, go to Contacts and find your friend's name to check whether or not you have his email address. If not, you need to add his email address.
3. On the iPad, go to settings>>messages>>recieve at>>add email. Put your friend's email address from step 2. It will say "verify".
4. Your friend need to verify by checking his email. There'll be an email from Apple. Open the email and he'll be asked to click on the verify link. Click on it and he'll be directed to Apple's homepage. Just follow the instructions there.
5. Once your friend has verified his email address, the word "verify" in step 3 disappears. Now you can iMessage him.
6. On your iPhone, go to contacts and choose your friend's name. Click on "send message" and choose the email address that was just verified. You're now directed to the message screen.
7. In the "To" field, you 'll see that the email adress is missing "@". Ignore it.
8. Make sure that the send button is blue. Now just type your message and send.

Hope this works!

psychotik, I think I figured this out. I was having the exact same problem as you. There was no way to type an '@' sign, and selecting from the contact list inside Messages app only shows phone numbers. I had to turn on "MMS Messaging" in Settings > Messages.

This enabled the @ sign on the keyboard for me. See:

I have no idea why this affects it. I feel like MMS should have nothing to do with whether I can iMessage someone, but it works for me, so I won't complain.