it wasn't working in 3.6 nightlies, so i tested on a clean profile of 3.5 w/ latest jetpack and latest stable firebug, but still not working. in about:jetpack i see the "incompatible firebug" message. in firebug i see the "you're using firebug with jetpack!" message. however, console.log doesn't log to firebug, but to the regular error console.
Firebug 1.4.2 still works for me, but we will be looking to get a much tighter, very predictable Firebug integration very soon!