I'll be purchasing an Iphone 3Gs upon my arrival in New Zealand next week and I'm running into some 'can I..' questions with the thing before I even buy it

Here's my situation:
For my trip I was planning on taking with me a good picture digital camera, a good video digital camera and a laptop. This is all quite bulky and I know that I wont get to use the video and the picture camera that much if Im forced to carry both around...and then there's the issue of the laptop itself.
But looking at the Iphone specs and capabilities... it turns out the Iphone itself replaces both the video camera and the laptop for what I need them to do (take pics/video, send email, browse the web, use google maps, etc). I will be taking my digital photo camera because it can change ISO, lighting, shutter speed, etc. settings to make the best pictures (and man do I abuse this ability

).
My picture camera has a USB camera->pc cable just like the Iphone does.
The problem is however.. without the laptop I cannot download the pictures from the photo camera (whereas the iphone allows you to use a wifi or 3G connect to download them to storage on the internet).
So I have:
1 X Iphone 3Gs with its own usb cable
1 X photo camera with its own USB cable
and I want to be able to connect the camera TO the iphone so that the iphone can download the pictures from the camera directly.
I know my camera, when connected to a PC, functions like an external hard disk (i've uploaded and downloaded pictures into the sd card this way). From what I read, the Iphone has the same capability.
So... why not connect the two and avoid taking the laptop altogether?
For that I'd need to have a cable that would have both ends as USB type A receptacle.. but I cannot seem to find any. Is this possible?
Skuzzy?