Short answer is no, not until they update pwnagetool for ios5.
However you can generate a custom ipsw using sn0wbreeze in parallels/fusion, then put you phone into restore mode using sn0wbreeze.
You can then restore the phone using the custom IPSW using iTunes 10.5 on your mac system. From then on you can use redsn0w tether boot your phone each time you reboot.