Since I have access to a 64bit platform, I can at least offer a data point. Here's what I get when running the snippet in the POD on an UltraSPARC-II (a quad-way E450):

Encoded: V30000W000004000
Decoded array: 15, 13, 8388608, 0, 549755813888
[download]

Looks like I get to sort out {,un}pack sooner than I thought, since this now has my curiosity :o)

(64bit OS, perl 5.6 compiled manually with 64bit ints, btw)

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Me spell chucker work grate. Need grandma chicken.