Here’s the scoop from the mono site:
After six month of extensive development, Martin Baulig has released the first version of the Mono debugger. The Mono debugger is written in C# and can debug both managed and unmanaged applications, support for multiple-threaded applications and should be relatively easy to port to new platforms.
Details of the release are available in post.
The debugger contains both Gtk# and command line interfaces. The debugging file format used in Dwarf (its already supported by our class libraries and the Mono C# compiler; To debug C applications, you need a recent GCC, or to pass the -gdwarf-2 flag to gcc).