I am pretty sure EINTR *is* the problem, but when I add the try, it seems that a later call to accept() throws EWOULDBLOCK (??). This doesn't crash Zope, but brings down the FCGI and PCGI Servers.

Ah, yes. that would do it... there are some oher changes needed to this function. I suggest you get the last version from the Zope CVS; revision 1.13 was the last one before it was deleted (or I can sent you it by email...)