Easy foreaches are also important . . . which leaves out C, C++, and Java

Java now has a foreach-like construct.

beyond obvious stuff like turing-completeness

I dunno. I think you could get some pretty nifty stuff in a language which isn't TC. Maybe it wouldn't work for general programming, but it may solve a specific problem domain very well.

Which is why I'm more interested in Parrot than Perl6, but that's another issue.