% perl5.8.8 -we 'use Devel::Peek; Dump $]' 
SV = PVNV(0x9f664d0) at 0x9f63ed0            
  REFCNT = 1
  FLAGS = (NOK,POK,READONLY,pNOK,pPOK)
  IV = 0
  NV = 5.008008                       #  <-- in 5.8 it was a number
  PV = 0x9f7d250 "5.008008"\0
  CUR = 8
  LEN = 12

% perl5.10.0 -we 'use Devel::Peek; Dump $]'  
SV = PV(0x9457198) at 0x946a610
  REFCNT = 1
  FLAGS = (POK,READONLY,pPOK)
  PV = 0x945e538 "5.010000"\0
  CUR = 8
  LEN = 12