Working for me. But, if <LS> is hanging it has to be because no \n is received. Add 2>&1 to the open command, maybe you are getting an error you aren't seeing due to not capturing STDERR.

#!/usr/bin/perl
open(LS, qq{ssh -p 22 onelesd\@localhost "if [ -d /home/foo/bar/201108
+26 ] ; then echo 1 ; else echo 0 ; fi" 2>&1 |});
my $baz = <LS>;
print $baz ;
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MacBook-Pro:Downloads onelesd$ ./script.pl 
0
MacBook-Pro:Downloads onelesd$
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