#Spot (SharpSpot) is a .NET library for Spotify communication, written entirely in managed code. It works well on your cell phone (.NET Compact Framework) and in Linux/Mac (Mono).
The library is based on Jotify (Thanks Felix!), and uses several open source components. See the list in the right column.
Please note that this is NOT (yet) a working application. This just gives developers an easy way of creating Spotify clients for .NET based enviroments and projects, like Windows Mobile and Mediaportal.