How do you make imessage work? The icon is there. You can type in the recipient but are not allowed to hit the send button

Question

How do you make imessage work? We upgraded to verision5. The icon is there. You can type the message but the send button is not available.

Answer 1

There is some instability in  iMessage.  It is a versatile and confusing app even though there are so few options in its use. 
I had issues trying to get iMessage work on both my iPads and my iPhone. 
ON the iPhone, turning off WiFi service and then trying iMessage fixed the problem.
On the iPad 2, same thing.  Turning off WiFi service fixed it.
On the iPad 1, I took a suggestion from zoomzoom and changed the WiFi network configuration on the iPad to use 8.8.8.8 as a DNS server and then use iMessage.  That fixed it.   Now I put the DNS back to default and it still works.
I suspect the iPod Touch will have the same fix as the iPad.
If you have a WiFi and 3G iPad or iPhone, try turing off WiFi and see if that fixes it. 
Why?  (beware, some of this is guesswork)
iMessage can talk SMS to cellphones and smartphones (that are using the cell-network).  It can also talk Apple iMessage format to iPhones and iPads whether they are on cell-network or on WiFi.  If you are talking to an SMS cellphone, iMessage figures that out and blindly sends your message.  If you are talking to a iOS5 device, iMessage figures that out too, checks to see that they are on-line, and then does something different if they are or are not on-line.  If you type in an email address, and not a phone number, I think iMessage attempts to see if the email address is registered with Apple (or iCloud or whatever) and if it is not, it does something to let you know, possibly by making the Send button not light up. 
In order to register iMessage and an email, you have to let the iOS device see whatever service it is that iMessage uses.  That is where the problem happenes.  zoomzoom suggested manually setting the WiFi DNS to google's 8.8.8.8 IP address, then run IMessage, and that seemed to fix the problem.  Setting the iOS device to use 3G-only (by turning off WiFi) also fixed the problem.  I suspect going down to StarBucks or McDonalds and using their WiFi would also fix the problem.  Once the problem is fixed, it doesn't seem to come back so I can't test these 'fixes'. 
To change the DNS on your iPad find your WiFi networks configuration, click on the blue arrow, touch DNS, backspace over the number that is shown, type in 8.8.8.8    Then click on the WiFiNetworks button at the top of the screen.  Now go run iMessage.  After that, you can delete the DNS entry again and leave it blank.  Your iPad will fill it in from the WiFi router when it needs it.