You can do something like that, though it isn't quite so direct.
A part of Condor is sometimes called Hawkeye, sometimes called "the cron
capabilities of Condor". The idea is that you can have Condor run scripts
for you on a regular basis, and the script outputs attributes that are
included in the ClassAd of a machine.
This will do exactly what you want. However, because it's a more general
mechanism, the setup is a bit more complicated.
You can read about it in section 3.3.8 of the Condor 6.6 manual. Look for
"cron". You should probably ignore STARTD_CRON_NAME for now.