In singleplayer, if you attempt to use the jetpack and don't have the Secret Weapons of WW2 expansion pack, the game will crash. So you will need that expansion pack for the mod to run correctly. Though in this latest version, you can at least play it now without the expansion pack. You just can't pick up the jetpacks.
In Multiplayer, the client should beable to connect to a server without having the xpacks as I ported the Jetpack over. Just won't work on COOP modes.
UPDATE: Finished uploading the incremental patch. Since this requires the full 1.5b installation, it should be ok to post the files here directly:
Client Files: (installer will overwrite older files without prompting)
http://files.filefront.com/13671297Server Files:
http://files.filefront.com/13679162Just run the EXE and it will update it for you.
Also, the server files are for remote servers. If you do not have one and do not have a server installation for this game, then you do not need it. Only the client files is what you need in this case.