After upgrading to #1421, RubyMine was unusable. I found a workaround and put my experience here in the hopes that it may help others (and RubyMine).
I am using Ubuntu Jaunty.
I updated to #1421 using, Help | Check for Update. This downloads the latest version and shuts down RubyMine.
When I started up RubyMine, a dialog asked me if I wanted to install the patch. Yes.
During this a warning dialog appeared. It indicated "a problem exists" and asked me to choose a solution. If memory serves, it listed the file ???/resources_en.jar, indicated the "problem" was "modified", and the possible solutions? Ignore. I chose "Ignore". Franky, I wasn't sure why it was showing this to me, but I translated it to say that that the resources_en.jar file was modified and, since I was updating, that sounded reasonable to me.
As RubyMine was starting up, I received a standard RubyMine Error dialog, but it indicated that the error had occurred > 100 times. 2 of 2 was very simple, something like "Too many errors. No longer monitoring." I sent the error (as mmscili), but the dialog did not allow me to enter a description.
When RubyMine completed its startup, the UI was incomplete. No menu, no tabs, partial view of an open file, no toolbars, no text in the title bar. Pressing 'X' brought up an incomplete close dialog.
As I was writing this, my teammate performed the upgrade as well. He had many more warnings (he thinks they all said modified and ignore). When RubyMine finally opened, it was even worse than mine. He had to leave shortly after, and did not get a chance to confirm this workaround.
After closing RubyMine. I moved my existing copy, downloaded the latest EAP from http://www.jetbrains.net/confluence/display/RUBYDEV/RubyMine+EAP, and (tada) a working RubyMine! It looks like all my settings were in the projects .idea folder, because I haven't found a missing setting yet.
Thanks for RubyMine.