Spokane Transit Authority has recently started crunching the numbers with agencies in North Idaho (including Kootenai Metropolitan Planning Organization) to determine the feasibility of implementing public transit between Post Falls and Spokane. At a recent 'Public Transportation Roundtable,' a new committee formed by KMPO, the discussion was what kind of route to provide; a through route with a variety of stops or a direct commuter route from Post Falls straight to downtown Spokane with limited stops. The consensus was to provide a little of both. The talks are in the early stages so it will still be a while before you can use public transportation to travel between Spokane and North Idaho.
In the meantime, here's a piece KXLY did on the situation yesterday.