What it says on the tin. When using a portal-style SignPortals, the game mode is not changed when switching worlds. Also, MultiInv fails to switch the inventories. I'm guessing some sort of WORLD_CHANGE signal isn't being emitted.

Hmm yea i'd heard this reported before but forgot about it, it should work fine, but I'll look at it tonight.

I can confirm this bug, running CB 1185, MV-Core 271, and MV-SP 121. Steps to reproduce:

1. Create a fresh server directory and set up CraftBukkit.
2. Install MV-Core and MV-SP. Op a user.
3. Create a world called creative; set it to creative mode. Import world as survival.
4. Log in the opped user; they will spawn in world. Give them obsidian, flint & steel, sign.
5. Make a standard Nether portal and ignite it. It will gain the purple goo. Do not move through it.
6. Attach a sign, second line [mv], third line creative. The second line will turn green.
7. Enter the Nether portal. The animation will play, and the following exception is emitted:

17:45:19 [SEVERE] Could not pass event PLAYER_PORTAL to Multiverse-Core
java.lang.NullPointerException
    at com.onarandombox.MultiverseCore.listeners.MVPlayerListener.checkWorldPermissions(MVPlayerListener.java:176)
    at com.onarandombox.MultiverseCore.listeners.MVPlayerListener.onPlayerPortal(MVPlayerListener.java:153)
    at org.bukkit.plugin.java.JavaPluginLoader$10.execute(JavaPluginLoader.java:307)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:58)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:338)
    at net.minecraft.server.ServerConfigurationManager.f(ServerConfigurationManager.java:308)
    at net.minecraft.server.EntityPlayer.b(EntityPlayer.java:278)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:305)
    at net.minecraft.server.Packet10Flying.a(SourceFile:126)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:92)
    at net.minecraft.server.NetworkListenThread.a(SourceFile:108)
    at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:464)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)

As described in the original post, the game mode does not change. No testing with MultiInv was done. In addition, the portal sent the user to the Nether (world_nether), rather than creative as expected; this happened despite world_nether not being imported into Multiverse.

Tested with only Core and SignPortals and it's fine. Will be testing with MultiInv, but this means it's most likely their issue an d not ours. Testing continues.

Finally fixed with 9054b6a