I've just experienced an anxious wait for Oreo to arrive in the US recently.
A normal 1 week transit time for Express Post turned into a v-e-r-y, v-e-r-y slow 2 weeks with absolutely no updates on the Australia Post tracking website, which by the way is normally very good.
Luckily for me, my wonderful collector had the patience of Job, although I think she was also starting to get a bit concerned at the time delay. Apparently the US mail is currently in high-security and all mail is being screened before going through the normal customs and distribution channels. They say this is supposed to only add around 48 hours to the mailing time, but I'm not sure where they got that figure from (probably the promotional department he! he!)
Anyway, all ended well: Oreo arrived safe and sound after his epic adventure and is now enjoying all the attention from his new mum!