After years of 3 dedications per show (since 1989 and Casey's Westwood One years) they took the number down to 2 in early 2004. Later in 2004 it would vary between 1 or 2 per show. Since the start of 2005, it has been taken down to one dedication every week (save one or two American Top 10 shows that featured 2)
I always thought 3 was a bit much...especially on the 3 hour shows. 2 was OK, but I don't mind only 1 per show. I doubt they are phasing them out. Maybe they simply realized one per hour was a bit much.