See a quote from Matt(hew) Ahrens (zfs developer)[0]:

  There's nothing special about ZFS that requires/encourages the use
  of ECC RAM more so than any other filesystem. [...] I would simply
  say: if you love your data, use ECC RAM. Additionally, use a
  filesystem that checksums your data, such as ZFS.

[0] http://arstechnica.com/civis/viewtopic.php?f=2&t=1235679&p=2...