Problem with libxml2-2.8.0 version on OS X Lion
You can do either of


remove /usr/local/lib/libxml2.2.dylib, copy a working libxml2.2.dylib from another Mac with the same OS X version and recreate the symlinks to look like the directory listing below
reinstall OS X Lion on top of the existing installation and reapplying all the system updates.
get libxml2.2.dylib from your backup and apply option 1


PS: I managed to do the same thing with one of the more essential libraries a few months ago, leaving only option 2 (because nothing useful worked anymore). With hindsight I probably could have booted from DVD to apply option 1, but I would still have needed a trusted source for the library because the DVD was for 10.7.0. 



pse@Fourecks:~$ ll /usr/lib/libxml2.*
lrwxr-xr-x  1 root  wheel       15 Feb 12 11:51 /usr/lib/libxml2.2.7.3.dylib@ -&gt; libxml2.2.dylib
-rwxr-xr-x  1 root  wheel  2321840 May 10 20:34 /usr/lib/libxml2.2.dylib*
lrwxr-xr-x  1 root  wheel       15 Feb 12 11:51 /usr/lib/libxml2.dylib@ -&gt; libxml2.2.dylib