in reply to RE (tilly) 1: substitution of variable within a variable
in thread substitution of variable within a variable

Another good pointer would be this entry in perlfaq7, which discusses the faults of symbolic refs.

update: another (better) discussion of the issue can be found here (by Mark-Jason Dominus).
  • Comment on (ar0n: see the faq) RE (2): substitution of variable within a variable

In Section Seekers of Perl Wisdom