FMACJ is a parallelization framework for the .NET CLR that gives your applications multicore/cluster support by saying what should be parallelized via attributes. You do not have to think about threads and networks at all. FMACJ also runs on Mono.
Alchemi is a .NET grid computing framework that allows you to painlessly aggregate the computing power of intranet and Internet-connected machines into a virtual supercomputer (computational grid) and to develop applications to run on the grid.