There is a new beta version of VirtualBox for Mac OS X available and installing Ubuntu Gutsy Gibbon worked like a charm (in opposition to Parallels). The only problem I encountered was, that it was not possible to mount a directory from the Mac OS X host in the guest system with either the internal mechanism (Folder sharing) and just directly via samba. In the latter case I could mount the host directory and could view it once, but than the mount was always busy and I had no access anymore. But I found another solution: sshfs. Here is a short introduction how to do that:

• Install sshfs via “sudo apt-get install sshfs”
• Add your user to the fuse group “sudo adduser user fuse” and logout/login to become member of this group.
• On the Mac OS X host allow ssh access: System Preferences->Sharing, Service “Remote Login”. Make sure your user is allowed to access via ssh
• Make a directory where you want to mount the host directory, e.g. “mkdir ~/MacDocs”
• Than mount a directory from the host with “sshfs -o uid=1000,gid=1000 username@server:/Users/username/ ~/MacDocs”. Here the uid and gid should be of your username, have a look in /etc/passwd. That’s it.
• Unmount the directory with fusermount -u MacDocs.

Links: http://wiki.ubuntuusers.de/FUSE/sshfs (German), http://ubuntu.wordpress.com/2005/10/28/how-………-sshfs/, http://wiki.ubuntuusers.de/SSH (German)

It’s also possible to have the directory automounted at system start, but I never managed to not enter my password or passphrase, so I just run a script with the “sshfs …” command if I need access to the host.