Still going! Though not shortest, I find this one amusing for some reason. Oh, and I have given it a name: "five substitutions".

#!perl -l
s--$"x$^F**pop-e,s-.-s,,,,s,$,/\\,,print,s,(?<=/.)..,$&^h9^gE,ge-ge
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Update: here is a more elaborate one - using a "ge" theme - mentioned in The Lighter Side of Perl Culture (Part III): Obfu (it takes a command line argument (1-9) indicating the triangle size):

#!/usr/bin/perl -l
s--@{[(gE^Ge)=~/[^g^e]/g]}[g^e]x((!!+~~g^e^g^e)<<pop).!gE-ge,
s-[^ge^ge]-s,,,,s,@{[(g^';').(e^'?')]},(G^'/').(E^'|')^Ge,ge,
print,s,(?<=/[^g^e])[^g^e][^g^e],$&^(G^'/').(E^'|')^gE,ge-ge
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