I ship cakes... but only those that are baked in a tube/bundt style pan. Here's what I do:
1) Place the iced cake on a slightly larger sized cake board... make sure you glue it onto the board with some icing. You can also skewer the cake to the board using some bamboo skewers. Flash freeze the cake until solid... fyi, that means uncovered; naked in the freezer -- the cake, not you. 
2) Fill the center hole with a parchment covered styrofoam cone that is slightly longer than the cake is high.
3) Place another cake board on top of the cone, then plastic wrap the entire thing... several layers thick.
4) Carefully place the wrapped cake inside a slightly larger cardboard hatbox... those sold at Michael's, Hobby Lobby, etc. are just fine. Or you can purchase pretty hatboxes elsewhere that are already decorated and intended to use as giftboxes.
5) Fill the gap between the cake and sides of box with bubble wrap. Make absolutely sure that nothing moves inside the box when you shake it. If anything is going to move, it's best that you discover it now.
6) Put the hatbox inside your plain shipping box... pad it snuggly with a ton of bubble wrap.
7) Mark the box "this side up". I always insure my packages!
8. Ship via Priority Mail... the cake will be kept fresh and will have thawed during the 2-3 days that it takes to reach it's destination.
HTH
DiH
Ok..so when do I get mine..lol
Y'mean it's not there yet???
Oh, wait..somones knocking.....!
Tee hee
PS: I can't wait to try your methods to ship my dad one of my cakes back up to NY state!
Thank you for your tips!!! 
It's really amusing to think of all of the different things we could come up with. Imagine someone marking it as questionable threat, only to open it up and see a cake. So many things seem "scary" these days seeing as who know what people do. I work with someone who's husband is a UPS driver. I'm going to ask her and see if she can find anything out from her husband.....I'll keep you guys posted.
Have transported long distances on my own.
Hey Darstus,
how did you transport your cake? I am making my own wedding cake and need to transport it 6 hours to the city we are getting married in. I definitely need to make it before the wedding day!
Thanks!
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