In my day we called them pound signs. The Bates Area Civic Association blog reported about the hashtag, regarding the September 8th meeting where two developers gave presentations regarding the vacant government owned property at Florida Ave and Q St NW. The hastag is #FlaQNW.
One of the developers has a email, (email@example.com) but no website. The other developer was a bit more old school and had big posters of what they hoped to do on the site.