I like this one, it's a lot faster than the average read-the-whole-file-and-then-see-what-the-last-lines-are-script.
And its usage is a lot cleaner than File::Tail's. Maybe you could wrap it in some nice module and put that on CPAN?

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
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