Good News.

(Readers of this thread might not think the news is so great, because I can't report on the --capture-image operation. My camera is a Canon PowerShot 530. It has a hardware switch that must be in one position for USB connection and the other position for taking pictures - therefore, no taking pictures via USB control. I might be able to try it with another camera some time.
Update on July 18: Also with 2nd camera, --capture-image operation is not supported. That's my last attempt for the time being. I am only interested in the --get-all-files operation myself.)

The .deb can be downloaded by Application Manager, which installs it flawlessly in /usr/bin, not /usr/local/bin. This is in everybody's PATH, and so gphoto2 runs without needing a full path specification.

You do not need to be root for the following commands:

$ gphoto2 --auto-detect
$ gphoto2 --summary
$ gphoto2 --list-files

To upload the pictures, I found I had to be root:

# gphoto2 --get-all-files

This works fine, but it sets ownership of the picture files as root, requiring a chown command before the Tablet's image viewer will display the pictures. Until then, files are greyed out in File Manager and can not be opened, deleted or moved using that application. To get over this, I use a short script:

#!/bin/sh
cd /home/user/MyDocs/.images
mkdir newphotos
cd newphotos
gphoto2 --get-all-files
sleep 1
chown -R user: .
chmod -R ugo+rwx .

(Note the colon-space-dot on the chown line and the space-dot on the chmod line. The position of these is crucial.)

If you use this script, your Images folder will get a new subfolder called "newphotos". You will usually find it best to rename or delete that subfolder before you run the script again.

Operation is rock-solid: never a crash, never a flicker. (Admittedly, I have not tried --capture-image, which seems to be the main interest of readers of this thread. Well, I did try it and got a message saying that my camera is not supported for that operation - no surprise.)

So why do I think this is such great news, when I have not tried the feature that everyone else wants? Well, If my wife and I take photos while travelling, our three other options for viewing and sorting them are:
(1) Take along Canon software CD and find an internet/PC cafe;
(2) Use RS-MMC in the camera and transfer it physically to the IT (which happens to be a 770);
(3) Put the camera's card in a USB card reader and mount it to the IT.

We usually take vacations in mountain villages with no internet cafes, and so option (1) is out. (Even when visiting cities, it is a major pain.) Options (2) and (3) are much more fiddly than writing one command, which is all gphoto2 needs to upload all the pictures. However, my real problem with options (2) and (3) is that I also use a mini camera which does not take a removable data card. gphoto2 works fine for uploading from the mini, although I have had to add some more code to the script, changing all file extensions to ".jpg" from ".ppn" .

Another reason I am happy is that I AM DOING THIS WITH A NOKIA 770. I am running gphoto2 on OS2008HE in a 704-MB partition of the MMC, which also has a 193.5-MB swap partition (no swap in the FAT partition). Apps written for OS2008 often fail to work on OS2008HE, especially if they involve USB or BT connections. It is particularly gratifying to find that this one does work. Very many thanks to darethehair for all his effort in bringing it to us.

P.S. -

gphoto2 --delete-all-files

did not do anything. It did not even send an error message. It just didn't delete. If I put that argument on the same line as --get-all-files, the files did not upload either. Am I missing something about the deletion command?

P.P.S. More good news, for anyone who activates USB host mode by inserting the host-mode modules and using the "echo host" command. (1) There are no conflicts with any of the standard host-mode modules; gphoto2 works with all of them loaded. (2) The only host module you need for gphoto2 operation is the host controller ohci-hcd on 770 (host controller is something else on 8x0), although you might also want to have usbhid for an external keyboard.

On the topic of USB host modules, can someone give me advice? I assume that, when I have more modules loaded than I really need, there is some price to pay, whether in increased power consumption or slower operation or less stability. I do not know this for certain, though. Does anyone have definite information on this?