For devices with a phone form-factor (I assume that is what you are asking)
then only those running the Smartphone 2003 Operating System contain the
Compact Framework v1.0. In terms of available handsets this very much
depends on your location and choice of available operators. There are a few
models around based on the HTC Voyager hardware (e.g. Orange SPV E200), and
Motorola's forthcoming MPx 100 and MPx 220 will have .NET Compact Framework
support.
There are also devices using the Pocket PC Phone edition platform. For all
Pocket PC 2003 phone edition devices (e.g. XDAII) the Compact Framework is
preinstalled in ROM, for older 2002 generation devices (e.g. the original
XDA) you can download and install the framework to the device.
To develop for these devices you'll need Visual Studio 2003 Professional (or
a higher edition). For Smartphone devices you'll also need the Smartphone
2003 SDK which plugs into Visual Studio and offers Smartphone specific
projects.
Peter