The real question is, what kind of photographer are you? Do you prefer snap-shots? Do you prefer artistic shots (like Art Wolfe)?
If you're just going to take photos for memory purposes, and maybe a print or two, then minimal gear should be sufficient. If you want stuff for the portfolio, then come prepared. Photography is understanding light, and second to that is knowing your gear for the purpose of capturing light.
I am one to pack too much, take too much on the first 1 or 2 excursions, then reevaluate my load if I need to. Every trip is the trip of a lifetime and some trips are the trips of multiple lifetimes. Traveling to Antarctica is, in my opinion, the ultimate trip a human can take on Earth in this day and age. If your pack is heavy, you'll only be straining during the short trip but you might have the equipment to get memories you'll enjoy the rest of your life.
Maybe I didn't read this thread close enough, but I'd say the only thing you're lacking is insurance. Things do not always go perfectly with gear. What are you doing for back-up? It looks like you have the glass to cover things, but what happens if your body takes a dump? Do you have a back-up body? What if you drop a lens off the boat? Will it be that critical focal length you can't live without?
What about protection? Read this article:
http://www.luminous-landscape.com/es...7-worked.shtml - serious photography trip and look at how many gear problems they had because of rain. You might want to look into some sort of rain protection (I use the Thinktank Hydrophobia) and a rain cover for your bag (I use the standard cover that came with my bag). Are you taking a laptop to move photos off the video card? What about a back-up harddrive or iPod to store your keepers on? What happens if a memory card goes bad (check out a program called Photo Rescue).
Yes, all this stuff adds up fast! I like the minimalist approach some of the other posters have suggested, but I like to be prepared. I'd feel like the trip was wasted if I couldn't get the best of my photographic abilities back from an excursion of this nature.
Here are a few things I threw together:
Gear I'm taking (keep in mind I regularly hike with more gear than this):
http://axspot.wordpress.com/2008/08/...tartic-voyage/
Clothing I'm packing:
http://axspot.wordpress.com/2008/08/...the-falklands/
And here's some stuff just on the trip in general:
http://axspot.wordpress.com/category/antarctica/