Wireless audio or media?
I'm sure you've guessed this, but some of the media adapters such as the d-link require a video output such as a tv in order to choose your music. The advantage of the Roku and the Squeezebox is that they have a built-in display, the Squeezebox has an 802.11g network making lossless audio much easier.
If I wanted to stream video or pictures, I would definitely consider the d-link. However, I'm going to use the Squeezebox to stream music to my multiple music systems as well as my home theater. Thus, I need the built-in display.