Yes, rung is a Scrabble word!
...and is worth 5 points in Scrabble, and 8 points in Words with Friends
rung
Verb
1. Sound loudly and sonorously
2. Ring or echo with sound
3. Make (bells) ring, often for the purposes of musical edification
4. Get or try to get into communication (with someone) by telephone
5. Extend on all sides of simultaneously; encircle
6. Attach a ring to the foot of, in order to identify
Noun
1. A crosspiece between the legs of a chair
2. One of the crosspieces that form the steps of a ladder
What Scrabble words can I make with the letters in rung?
3 Letter Words
2 Letter Words