TerminalPatch is a project mainly written in OBJECTIVE-C and C, it's free.
New Terminal tab/window with same dir
Simbl plugin for Terminal to open new tab (⌃⌘T) or window (⌃⌘N) with same dir. Indifferent to business of original tab.
Puts patches on Terminal icon
You need SIMBL.
Put bundle in folder /Library/Application Support/SIMBL/Plugins or ~/Library/Application Support/SIMBL/Plugins and restart Terminal