To get PCManFM 1.0 in the best shape possible we just put a release candidate on the sourceforge file archive. Notable changes include external thumbnailer support, new file attribute dialog, support for modifier keys on drag and drop, symbolic link creation, individual wallpapers per desktop and documentation.
You will need libfm 1.0 to use pcmanfm 1.0 so they are released as a pair as usual.
Bug reports and patches should be submitted to the trackers at sourceforge. For bug reports be as specific as you can and try to cooperate with the developers if they ask for further testing. Hanging around the IRC channel #lxde at irc.oftc.net and reading the PCManFM project mailinglist are other good ways to interact with the project.
Get libfm and pcmanfm from the sourceforge file archive:
libfm-1.0rc1.tar.gz, sha1sum: 37528cde92dcbb1663c6c9d3eaf7fee51aacda8e
pcmanfm-1.0rc1.tar.gz, sha1sum: 4f28151b07934ffc99a6f3b697916055e45d2485