Net60 - .NET for Symbian Powered Devices
RedFiveLabs have recently introduced Net60's Beta1. Net60 is .NET Compact Framework implementation for Symbian. Symbian is a widely used operating system on Nokia and other mobile phone manufacturers. Net60 Beta1 is the first runtime which has the support to run "on device", their earlier releases were only for emulators. Being beta, currently it only supports S60 3rd Edition (Feature Pack 1 and 2) and Symbian OS 9.0, 9.1 and 9.2 devices only.
Net60 will be .NET Compact Framework v1 compatible. Many enterprise apps uses databases; many Windows Mobile devices are shipped with SQL Server' Compact Edition (or you can download and install it separately). One thing to understand is that SQLCE is not .NET app its a Windows Mobile native app with .NET drivers...so basically even with Net60 you will not be able to use SQLCE; you have to use some Symbian based database engine or some pure .NET based database engine.
Net60 Beta1 is offered as unsigned SIS package; you need to use SymbianSigned to get the development certificate and then using S60 SDK (which required Perl) you can sign the SIS package before installing to your S60 device. I just have finished doing all these steps which are outlined here and now I can use Visual Studio to make some apps for my Symbian powered mobile device in .NET
Nokia's Carbide.vs is another offering to develop native Symbian apps in C/C++ using Visual Studio.