Yes to just about any IP device that has a UPnP/DNLA client.

As you surmise receivers, pre/pro's, TV's, Blu-Ray players and media centers now all come with streaming clients. I find these proprietary clients lack the features and robustness of the open source alternatives.

All you need is a server that streams audio (or video). There are many such options from open source media server software like XBMC to proprietary solutions from Apple.

The benefit of the client/server approach is you probably have a computer that can act as a server. For example a windows box can run something like Tversity (tversity.com) or if you have XBMC running it can mount smb network shares or other file services and stream the contents to clients.

My current solution is a dedicated XBMC media center in the living room that connects to the media file server over a gigabit wired network and acts as a streaming server to devices and as an airplay service for devices. Any device that supports the protocol can connect to xbmc and thus access all the centralized media files. This was all done using off the shelf standard components.

gord