See response from O2, seems like WM6 is still in the pipeline :
Thank you for contacting O2 Asia Technical Support.
With regards to your response below, kindly be advised that our engineers are currenly testing the Windows Mobile 6 on Xda Flame. However, kindly note that there is no news at the moment regarding the release date of Windows Mobile 6 on Xda Flame.
Should you require any further assistance, kindly reply to this e-mail. Thank you.
Warmest Regards,
O2 Technical Support (Email)
Asia Pacific Region
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