gc: Lua vs. Python

[Enrico Colombini <erix@...>]

While discussing Lua with a colleague, I've been told that Python's gc 
has no limitations. I vaguely remembered otherwise, by my recollections 
could be out-of-date.

Could somebody point out the gc differences between the two languages?
(I know that Python can also use reference counting, but it's gc I'm 
interested in)

  Enrico