Yeah I love the idea behind qira: each instruction run is like a git commit. It uses qemu to record all the information and then you can search through it.
The rr debugger works on the same sort of idea: http://rr-project.org/
The qira presentation he gave was great fun: https://www.youtube.com/watch?v=eGl6kpSajag

For a while I had been frustrated with gdb (crashing and/or the UI mangling itself) and starting thinking about a scriptable debugger - it turns out plan9 has one http://plan9.bell-labs.com/sys/doc/acidpaper.html
I still think this idea could be really profitable (especially compared to piping your commands into gdb..) but it's a lot of effort working with ptrace to actually implement one.