Sony Ericsson W999 combines features of W580 and M600 models in one GSM slider phone. It will soon be available.
W999 will have HSDPA for fast internet speed. A 2Mpix camera will probably be present, but there will be no for video calling. The device will have a 2.4" QVGA screen and should be only 0.5" thick (12.5mm)
Currently there is no info on Walkman W999i phone.