Debian

###Official Packages Official Debian packaging of SpaceFM and udevil is underway (currently spacefm is uploaded to mentors here and udevil is here). You can provide encouragement here and here.
SpaceFM is already available on Debian Testing.

###Self-Building Packages Additionally, self-building deb packages for all Debian-based distros (Lenny and later) are available in Downloads for SpaceFM and udevil (to save a file, click on its filename and click 'View Raw'), and are also available via the author's PPA as spacefm, spacefm-gtk3, spacefm-hal, and udevil. These convenience deb packages contain the source code and require SpaceFM's build dependencies, and $TMPDIR (usually /tmp) must NOT be mounted noexec.

###Build A Binary Package Or easily build your own binary deb package from source using the instructions in the README.

###For Debian Squeeze If you have trouble installing libgtk2.0-dev, you may need (from Crunchbang forum):

sudo apt-get install -t squeeze-backports libgtk2.0-dev

(does this fix only apply when using Crunchbang backports?)

###Ubuntu From Issue #49:

If you want to have the menus in view from the 'dash' launcher in Unity you need to do the following:

cp /usr/share/applications/spacefm.desktop ~/.local/share/applications/
gedit ~/.local/share/applications/spacefm.desktop

Then edit the Exec= line in that file to:

Exec=env UBUNTU_MENUPROXY= spacefm

Note some other Unity issues, most with workarounds.

###Lubuntu Mateusz Łukasik's PPA provides SpaceFM packages.