I've just released call_stack: backtrace data and 1.8.5-safe breakpoint/Binding.of_caller, which provides an alternative
Binding.of_caller implementation and some additional functionality to obtain
backtrace information (the "call stack"). You can override a pre-existent
binding_of_caller.rb by loading breakpoint185.rb:
ruby -rbreakpoint185 myapp.rb
Here's how you'd use it with Rails' breakpointer:
put the breakpoint calls in the code you're inspecting, as usual
start the "breakpointer" as usual with script/breakpointer
run the application with ruby -rbreakpoint185 script/server