As usual while waiting for the next release - don't forget to check the nightly builds in the forum.
Is there any way to do this? I can't see it from the wiki, but again I might be doing something daft! For AVR targets, the default output is not an exe.
target.SetTargetFilenameGenerationPolicy(tgfpPlatformDefault, tgfpNone);
target.SetTargetFilenameGenerationPolicy(tgfpNone, tgfpNone);