This was fine, except that it seemed extremely flaky on all our test servers - randomly crashing, sometimes taking out a running VM with it.
It turns out that this is all the fault of our running an up-to-date version of SL. SL5.4 (actually, anything based on RHEL5.4, one assumes) has a version of glibc that VMWare really doesn't get on with well.
Once we copied the 5.3 release of libc.so.6 from a 5.3 server into a suitable place, and pointed VMware's LD_LIBRARY_PATH at it, it seems much more stable.
(The relevant bug report, including fix suggestions is: