A Tango ROM has leaked on XDA-Developers. Tango Build 220.127.116.1173 has been made available for download by Football, ready to be cook into ROMs.
Besides the optimizations for low memory, Windows Phone Tango brings improvements in MMS messaging and bug fixes, including fixing the SMS of Death vulnerability.
Despite the improvements the official roll out of the Tango update to Windows Phones will be dependent on carriers.
Read more in this XDA-Dev thread.
Thanks Jose for the tip.