InfoWorld reported that Microsoft plans to have a Windows 7 release candidate in late May. They reported the information from Neowin.net. The information states that the release candidate would be available the last week of May. Knowing that Microsoft's Tech Ed event is in May of this year, it seems that there is an obvious target date for such an important milestone to happen!
Also mentioned was a first (private) beta of Office 14 in early July and a second beta in early November (PDC?).