I understand what the .Net Client Profile is, but what does "PREVIEW" mean? (http://www.microsoft.com/downloads/details.aspx?familyid=8CEA6CD1-15BC-4664-B27D-8CEBA808B28B&displaylang=en)
Is this like a beta release? Is it safe to deploy alongside my application?
It does look like the title is in error, because it says RTM further down on that page.
HOWEVER, a new version of 3.5 SP1 (known as 3.5 SP1 GDR) is about to be released any day now, to fix regressions which were in SP1. You might want to wait for that before a big deployment.
I think that is a mistake in MSDN. It happens. Client Profile is "RTM", so no: this isn't a beta release AFAIK. I will try to look a bit more...
Really interesting question, BTW!
As I understand it, the difference between a BETA and a PREVIEW in MS parlance is that a BETA's feature set is pretty much fixed while a PREVIEW, though it should be of a similar quality, may still see significant feature changes.