Not really, it is just that DreamHost has decided to use Linux for their servers, this would make it difficult for them to support Microsoft technologies such as ASP and ASP.NET.
If you require these technologies for your site, you really should have chosen a Windows based host.
PHP is supported, of-course, as is Ruby, Perl and Python.
Unfortunately, Coldfusion is not supported either. As I understand it, this too is primarily a Windows based technology.
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