$ mv .ssh/ .ssh.old/
$ python
>>>import gnomevfs
>>> gnomevfs.get_file_info( "ssh://aigarius:password@aigarius.com/home/aigarius" )
Traceback (most recent call last):
File "<stdin>", line 1, in ?
gnomevfs.AccessDeniedError: Access denied
>>>
$ ssh aigarius.com
The authenticity of host 'aigarius.com (85.254.216.40)' can't be established.
RSA key fingerprint is 6d:29:c0:f3:d0:84:c9:a9:d9:4c:7e:e3:1a:18:a2:e2.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'aigarius.com,85.254.216.40' (RSA) to the list of known hosts.
aigarius@aigarius.com's password: *******
[...]
aigarius.com$ exit
$ python
>>>import gnomevfs
>>> gnomevfs.get_file_info( "ssh://aigarius:password@aigarius.com/home/aigarius" )
<gnomevfs .FileInfo 'aigarius'>
>>>


Of course, this is mentioned nowhere in the sparse documentation. Please keep me away from the person who wrote GnomeVFS and its Python bindings. Bloodshed might ensue. Bug reported

Why can't someone write a nice, light, working network file transfer protocol abstraction library that would be independent of any desktop environment (bonus) and a working X server (I am looking at you, GnomeVFS). Something that would simply provided all file and folder manipulation operations in sync and async ways in such way that those operations work completely uniformly across all supported protocols. Support for at least ssh and ftp is essential, webdav, nfs, rsync and other protocols that allow writing files to remote locations and http, https and other protocols that only allow read only access to remote files would be very welcome. The library should be in C with bindings in C++, Python, Perl, Ruby, PHP and also a command line processor that would allow all commands to be used in a shell script.
Why something like this can not be written and obsolete the GnomeVFS and those KIOslaves. Freedesktop.org, I am looking at you, please!

Update: Apparently I only need to "import gnome.ui" and execute "gnome.ui.authentication_manager_init()" and my application will automagically get a proper authentication dialog in this case. Unfortunately it is not documented anywhere that I could find. :P