Yesterday the June 2008 CTP of Microsoft Parallel Extensions to .NET Framework 3.5 was released. There is also an MSDN developer centre. I watched a 20 minute video which walked through some of the samples - worth a look. The presenter (Daniel Moth - "the Moth") said that they are focused on the API surface at this stage in the lifecyle and not much has been done on performance. Look in the download at the chm doco for some good ideas about how software can start to take advantage of multi-cores.