I am now using my new iPhone to control my iTunes library on the MacBook Air and can't wait to get an AirPlay speaker system for the bedroom. A very easy to use and elegant solution. Thank You Apple!
Mountain Lion appears to work well with Tim Burson's BitPerfect also.
13.3" MacBook Air, 4GB RAM, 256GB SSD; iTunes/Bit Perfect; MacBook Air SuperDrive; Western Digital My Book Essential 2TB USB HD; Schiit Bifrost USB DAC; Emotiva USP-1, ERC-1 and two UPA-1s; Pro-Ject Xpression III and AT440MLa; AKAI AT-2600 and Harman Kardon TD4400; Grado SR80i; Magnepan MMG Magnestands; and, Rythmik Audio F12