If you have a verizon iPhone and its failing to update to 4.2.6 giving error 1013, remove the gs.apple.com from /etc/hosts and then run dscacheutil -flushcache and try again. I think saurik's shsh server isn't properly handling the vzw TSS request.
Save your shsh with tiny umbrella after the update to 4.2.6.
Save your shsh with tiny umbrella after the update to 4.2.6.