The word harbingering is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 23
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (34 words)
angrier, baggier, banging, barging, barring, bearing, biennia, binging, bragger, bringer, brinier, earning, earring, gaining, garbing, gearing, girning, grainer, grinner, hairier, hanging, hearing, herring, hinging, ingrain, nearing, raggier, rainier, raining, rangier, ranging, rearing, reining, ringing