I have set up a VirtualBox Fedora 11 (i386) guest on my Fedora 11 (x86_64) host system with shared folders enabled. I mount the shared folder successfully with the recommended "mount -t vboxsf share /shareddir -o rw,exec,uid=500,gid=100" command. I can successfully read and write files in the share from the guest but I cannot set the execute bit on any file in the share from the guest system. Nothing in GoogleSpace seems to address my issue let alone provide a solution. fwiw, selinux is disabled on both the guest and host and the shared folder is an ext4 file system.
This sets the executable flag in the guest only (mode 700) for all shared files — the host still always gets mode 500 for newly created files. Hopefully a dev can make a proper fix. (slight improvement: set executable on new file creation, and keep file permissions in sync otherwise so non-executables in the host don't show up as executable in the guest)
At least this lets me do development within a shared directory.