After buying the building at 549 Myrtle Avenue in 2005 for $2,140,000, the developers have finally started to shift into gear recently, encouraged, perhaps, by news of the Hudson Companies project down the block that should greatly increase the attractiveness of the general area. Demolition began recently and preliminary plans, we hear, call for a four-story residential building. Unlike some other projects in the neighborhood, the one actually benefited from last year’s rezoning. GMAP P*Shark DOB