A quick look at getting Backburner status information using MAXScript, based on the documentation in the MAXScript help file on NetRender (mainly the examples at the end of the page).

Make sure that a job is running before running the code (after the job ended before i finished tested i submitted a 10000 frame job of a box, no output file and task blocking not enabled, that kep it busy logn enough).

First we need to connect to the manager, take control (my assumption is that i'm the only one, if the Backburner monitor is running at the same time you'll get an error - so you may want to put some error checking in place) and lock access:

m=netrender.getmanager()
m.connect #manual "bbmanager"
m.getcontrol()
m.Lock true

Then we get a list of jobs and a list of servers (and we make sure that the job and server lists don't get updated whilst we get them):

m.SetUpdates false
j=m.getjobs()
s=m.getservers()
m.SetUpdates true

Then we loop through all servers and print the name and frame index of the current job it's working on (returns undefined if the server isn't working on a job) 

for srv in s do
(
 print srv.name
 print srv.jobFrameIndex
)

And finally we disconnect:

m.disconnect()

If you want to get more info on jobs you could run this before you disconnect, note that on large jobs it takes a while to get this info!

for job in j do
(
 l=job.GetLog()
 print l
)

You can download the file here: backburner-status.zip