OK, here's the deal. My wife is just going into labor with our second child. To keep the family updated I set up action streams on our blog with my twitter feed. There were a few issues with automatically rebuilding the index template, but otherwise things were going well.
Just before she started labor I made the mistake of trying to upgrade to the SVN version to fix some of the minor issues. Now it's not working at all. In the Activity Log I see this:
pjmckellar): Can't locate XML/XPath.pm in @INC (@INC contains: /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/WXRImporter/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/TypePadAntiSpam/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/WidgetManager/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/spamlookup/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/StyleCatcher/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/feeds-app-lite/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/MultiBlog/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/Textile/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/ActionStreams/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/addons/Community.pack/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/addons/Commercial.pack/lib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/extlib /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/extlib lib /etc/perl /usr/local/lib/perl/5.8.4 /usr/local/share/perl/5.8.4 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.8 /usr/share/perl/5.8 /usr/local/lib/site_perl .) at /nfs/c02/h06/mnt/23917/domains/mckellars.net/ cgi-bin/plugins/ActionStreams/lib/ActionStrea ms/Event.pm line 232.
I tried reverting back to the 1.0 version (by simply copying over the 1.1 files) but I still get the same error. Anyone have any ideas? I'd love to get this working before we leave for the hospital!
Reported on Movable Type 4.2

Hi Peter
By default, MT ships with a file called XPath.pm in your MT_DIR/extlib/XML folder (there's also an XPath directory in there). Double check those are there - if not you can download it. Extract that download and upload the contents of the lib folder into your MT_DIR/extlib folder.
Hopefully that fixes it.
Congratulations and good luck with the baby :)
Arvind - you're a lifesaver. I thank you and my family thanks you. That did the trick!
One more minor issue (that caused me to do the upgrade in the first place). When the cron job executes, it throws this error in the activity log:
Action Streams died with: Can't locate object method "user" via package "MT" at lib/MT/Util.pm line 260.
If I rebuild manually the posts show up, but the cron job always dies with that error. Any thoughts?