You may want to make some installation instructions (usage) for the windows apps. If I didn't know any better, I'd try entering the full url http://www.someserver.com/DeskTopModules/iWeb/webservice.asmx (which actually, I did at first and got all sorts of fun errors). Once I realized that you are probably already adding the last portion (DesktopModules/iWeb/webservice.asmx) automatically, I entered just my server info and then it worked.
The GetUser method (in the core connector) makes it sound like you are asking for their UserId (integer) when in reality you are looking for a user name. Probably want to make that a little more intuitive.
I'd like to see Drag/Drop enabled on the IWeb Explorer, if nothing else, at least drag/drop files and folders onto it for uploading. I realize downloading is a different story.
Can you tell me how you got the different icons and type to show up for your files? (in other words, how is that app smart enough to know what the file type is?)
If you click "properties" and you don't have a file selected, it crashes the IWeb Explorer.
Tile view mode looks awful, superimposes the icons all over each other and ends up not being usable.
Back and Forward buttons don't seem to ever do anything.
ListPortals, double click on a portal, try to save and watch it crash and burn.
DeleteFile should prompt the user and make sure they really want to do that. Need a DeleteFolder option.
Other than that, things are looking peachy!