Last year saw the debut of Steam Dev Days, in which a gathering of developers received information on the service and Steam Machines. For those that thought this was going to be a yearly occurrence, this won't be the case.
Valve has confirmed with Gamasutra that there won't be a Steam Dev Days this year and the only time they will schedule one is if they have something to promote. They'll be at GDC with a bigger presence, but for now, there isn't a Steam specific one planned.
Perhaps they'll have one once Source 2.0 is finally released.