Mobile Tech World spotted the job listing alongside another for a Software Test Engineer position that appears to be related. The description mentions mobile gaming and always connected devices, as well as the "opportunity to make a critical impact the next release of Windows Mobile." Sadly, that last part in particular suggest that users may have to wait until the release of Windows Mobile 7 in late 2010 before seeing any of this.
Microsoft's strongest commitment to mobile gaming so far has been the launch of Zune HD games. It remains to be seen what will this mean for the Tegra-equipped portable media player if Windows Mobile is to become the Xbox LIVE portable gaming platform.