I believe this when I see it. Until then, I would assume your coins are gone.
Shows a lack of understanding of how Bitcoin works.
There are no coins so there is nothing which can be "gone". MtGox has the private key and hasn't lost or compromised itso either:
a) the tx will eventually be confirmed and then every node will "see" it.
b) the tx was flawed and will be forgotten by the network in time however in that case MtGox will still have the unspent output (value) used in this transaction.
There is no scenario where coins can just be "gone" unless you lose the private key (or send them to an address where the private key is unknown).