When I invoke the context menu on a .zip, a tar.gz, there is a submenu which proposes me to compress that file in various formats, again.
Shouldn't these menus be hidden ?
Also, the submenu Extract Archive Here, Autodetect Subfolder is unclear; I think it's supposed to first create a folder, then copy the file in this folder, then uncompress the file.
If Dolphin knows the name of the folder it's going to make, why doesn't it write this name in the context menu ?

From: http://docs.kde.org/stable/en/kdeutils/ark/ark-in_filemanager.html
Extract Archive Here, Autodetect Subfolder creates a subfolder in the folder with the archive and extracts the folders and files into it.

Shoudln't this be labeled Autocreate subfolder + [name of the new folder] ?

There is another problem I just noticed: the view doesn't (always) update after the uncompression process is done. This is disorienting.

In regard to the recompression options, I could not reproduce that under KDE Trunk in Dolphin.

For the other options - it seems the "Autodetect" option means that it will check the archive to see if the first level contains a single folder and no files. If this is the case, it will simply directly extract this file. If this is not the case, it will create a folder and extract the archive contents into that new folder.