WordNet (r) 3.0 (2006):

heartening
    adj 1: cheerfully encouraging [syn: heartening, inspiriting]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "heartening":
   animating, assurance, assuring, cheerful, cheering, cheery,
   comforting, condolatory, condolent, condoling, consolatory,
   consoling, emboldening, encouragement, encouraging, enlivening,
   exhilarating, glad, gladdening, heart-warming, hospitable,
   inspiration, inspiring, inspiriting, inspiritment, invigorating,
   joyful, of good comfort, reassurance, reassuring, relieving,
   supportive, sympathetic