ditto vs zip
Obviously before Tiger the zip command did not support resource forks. So in order to zip stuff up properly you were meant to use ditto.
ditto -c -k -X --rsrc some_folder some_folder.zip
…which is what finder uses to create archives, too. From the man page it seems in Tiger resource forks are supported by default:
-df [MacOS] Include only data-fork of files zipped into the archive.
Good for exporting files to foreign operating-systems.
Resource-forks will be ignored at all.