Has the "path to" command changed in Mac OS X?

Yes. While this might not be a complete list of changes in regard to this command (after all OS X is a work in progress), it is certainly very comprehensive. Note that some of these paths behave differently in the current version of OS X than they did in the earlier version(s).

The “path to” command is useful for determining and targeting specific locations on the computer. For example, you can use this command to locate the System folder or Applications folder regardless of how the user has named their startup disk.

OS 9 and earlier OS releases were designed to be mostly a single domain, single user system. Although it can be used in much the same manner as a single user system, Mac OS X is inherently multi-user environment and as such can be run from one of four domains: the System domain, the local domain, the network domain, and the user domain, each of which has its own destinations, permissions, and folder locations.

The “path to” command now has an optional parameter for determining the appropriate path for the requested location. Here are many of the new paths:

path to preferences folder from user domain
--> alias "Mac OS X:Users:yourName:Library:Preferences:" 

path to preferences folder from local domain
--> alias "Mac OS X:Library:Preferences:" 

-- HELP FOLDER 
path to help folder from user domain
-- alias "Mac OS X:Users:userName:Library:Documentation:Help:" 

path to help folder from System domain
-- alias "Mac OS X:Library:Documentation:Help:" 

-- DOCUMENTS FOLDER 
path to document folder from user domain
-- alias "Mac OS X:Users:userName:Documents:" 

-- APPLICATIONS FOLDER 
path to application folder from System domain
-- alias "Mac OS X:Applications:" 

-- SOUNDS FOLDER 
path to "ssnd " from System domain
-- alias "Mac OS X:System:Library:Sounds:" 

-- FAVORITES FOLDER 
path to "favs " from user domain
-- alias "Mac OS X:Users:userName:Library:Favorites:" 

-- LIBRARY FOLDERS 
path to "dlib " from user domain
-- alias "Mac OS X:Users:userName:Library:" 

path to "dlib " from System domain
-- alias "Mac OS X:System:Library:" 

path to "dlib " from local domain
-- alias "Mac OS X:Library:" 

-- HOME FOLDER 
path to "cusr " from user domain
-- alias "Mac OS X:Users:userName:" 

-- TEMPORARY ITEMS FOLDER 
path to temporary items folder
-- alias "Mac OS X:private:tmp:501:Temporary Items:" 

-- USERS FOLDER 
path to "usrs "
-- alias "Mac OS X:Users:" 

-- ROOT FOLDER 
path to "root " from System domain
-- alias "Mac OS X:System:" 

path to "root " from user domain
-- alias "Mac OS X:Users:userName:" 

path to "root " from network domain
-- alias "Mac OS X:Network:" 

-- SHARED DOCUMENTS FOLDER 
path to "sdat "
-- alias "Mac OS X:Users:Shared:" 

-- SCRIPTS FOLDER 
path to scripts folder from user domain
-- alias "Mac OS X:Users:userName:Library:Scripts:" 

More info regarding four-byte codes, here.