Using Mac OS X, to open a Finder window in the current directory (current path) of a Terminal window, just issue this command:

open .

(Yes, that is a decimal after the open command.)

For instance, if you have a Terminal window open, and you're working in the /tmp directory, and you issue this open command, the Finder will be opened, displaying the contents of the /tmp directory.

Other "open" magic

The open command can be used in a many other ways as well. For instance, if there's a file named EmailAddressValidator.java in the current directory and I type

open EmailAddressValidator.java

at the Terminal prompt, this Java file will be opened by TextMate, which I've configured to be the default editor for files ending in a .java extension.