Yeah this is true, but for some of us this is acceptable.
Linux users are an additional market for the product I help develop and we have never really worried about it. I have been waiting for this mono milestone before bothering with mono, however now that they are there I dont mind putting the resources in and testing the waters.
If everything goes smoothly I can see us offering a linux flavour very soon. Our current product operates on .NET Framework 2.0 SP1.