I have seen this for a good while even as far back as Jive Messenger.
The ethereal sniffed packets below are the proof. In my opinion Wildfire should not alter the contents of the message (period) unless it needs to escape some special XML characters.
Message from sender to receiver
0040 fb 70 3c 6d 65 73 73 61 67 65 20 69 64 3d 22 33 .p