And you don't want to use Stackless Python because ... ?

I was going to suggest that Stackless is dead, given that I haven't heard any news about it.

But that would have been foolish of me: http://zope.stackless.com/Members/rmtew/News%20Archive/3.1.3

As far as I know, they haven't developed any significant new features (does it need any?) in a long long time, so in that sense it's not an "active" project. But they're usually quick to port their patchset to each new Python version.

It adds coroutines to Python. What more do you need? It runs every other Python package, it tracks new Python releases perfectly, which means its "significant new features" are identical to Python's significant new features.

What would an "active" version of the project look like?

There is also continued work on coroutines (based on Stackless) in Pypy: http://codespeak.net/pypy/dist/pypy/doc/stackless.html

Thanks, I'll check this out in addition to stackless.

stackless is actively used by mmorpg EvE Online

Meh, I could nitpick at the language all day but I still use it. Call/cc probably isn't happening anytime soon.

So keep using Lua? Langauges choices are all about that...choice.