Blatantly stealing from http://ss64.com/ps/syntax-openhere.html, you basically need to save the following to a text file with an extension of .reg, double click to run it and confirm the input. Now when you right click on a directory, you will have an option for "PowerShell Here".
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Directory\shell\PSOpenHere]
@="PowerShell Here"
[HKEY_CLASSES_ROOT\Directory\shell\PSOpenHere\command]
@="C:\\Windows\\system32\\WindowsPowerShell\\v1.0\\powershell.exe -NoExit -Command Set-Location -LiteralPath '%L'"
In Vista and Windows 7, you'll get that option if you hold down shift and right-click (this is built in).Does anybody know how this might be changed to use the PowerShell instead? – orschiro Jun 2 '12 at 10:31