I picked up a UA leaflet at IAD yesterday, detailing their move on 4 July to T1 and the new *lounge. The leaflet mentions "distinct first and business class areas". I hadn't seen this mentioned before.

I presume the F area will be for F passengers only (as UA's F lounge was), rather that the LH/BD differentiation between DC/Senator and Business lounges. (Which I know has been confused by the addition of the LH F lounges in MUC and FRA().