On Mon, 13 Oct 2008, Tobias Burnus wrote:

> Hello,
>
> using
>
> \enableregime[utf]
> \starttext
> Σ, σ or ς?
> \stoptext
>
> with pdftex prints "Σ, σ or σ?" (but the latter should be a \varsigma
> and not a \sigma). And with LuaTeX the result is even "Σ, or ?", i.e.
> the small sigmas disappear completely.

If you try this in math mode, pdftex displays the same bug, but with 
luatex, \varsigma comes out correctly. I do not know why  ς does not work 
in text mode in luatex.

Aditya