dist-upgrade to current unstable leads to all sorts of weird segfaults on a dual G4 running a recent 2.4.2pre kernel here, including with locally compiled apps. One example I have in mind is gkrellm (who works perfectly well on another box using a slightly older snapshot of unstable).
libc issue ? If it's not a known issue, tell me and I'll try to investigate it later this week (this is not my box) Ben.