More folks are using Linux to control equipment. Users range from amateur astronomers in the field to professional observatories.
KTelescope is a robust Client/Server control library for Meade's LX200 based telescopes. It uses the Instrument Neutral Distributed Interface (INDI) protocol.
INDI is an instrument-neutral distributed interface for operating any remote device over a reliable byte stream interface. There is an active group writing an expanding list of drivers for astronomy related equipment including telescopes and cameras at sourceforge.net.
XEphem has the capability to control several telecopes and other devices using the Instrument Neutral Distributed Interface (INDI) protocol.
Apogee Instruments Inc supports their line of professional CCD cameras under Linux.
Finger Lakes Instrumentation Manufacturer of CCD cameras and filter wheels and include drivers for Linux.
SBIG offers some assistance with operating their ST7 and ST8 CCD cameras under Linux.
CCD Astronomy on Linux These pages describe a number of facets of using astronomical CCD cameras for image acquisition and processing under Linux.
Gccd is a gnome-based CCD camera and filter wheel control program.