It seems that for options[:position] to work in edge rails now, you must specify "'bottom'" instead of :bottom. Prototype is expecting a string here, and if you feed it the symbol the javascript is written as {insertion: bottom} which results in a javascript error.
I'm not sure what's changed to make this so. If it's something with Rails/Prototype and not something that I changed in my app, then the documentation for link_to_remote should reflect the change.
