Q1 to Q3 seems a relatively short time for OEM testing, so it's either with key OEM parteners (HTC for example) already or Q3 2010 is optimistic.
ZDNet state that Microsoft is increasing the rate of development for WM7 to try and boost market share.
According to ZDNet Taiwan, Microsoft is set release Windows Mobile 7 to OEMs for testing in Q1 2010, with a launch date set for Q3 2010, a year after the launch of Windows Mobile 6.5. WMPowerUser talk of a “Maldives” program to gather feedback from OEMs, though those famailiar with WM6.5.1 branches may have heard of MD1 which is where a lot of the UI changes come from.
Whatever happens, lets hope WM7 is as good as it's supposed to be!