Why does Google Chrome mount and unmount a volume every few hours? I'm assuming it's part of the 'check for updates' process, but does anyone know how this is controlled and what it's mounting and unmounting?  

I first discovered this behavior after updating Growl, and I ran HardwareGrowler to see what it did (it was a slow afternoon) and it's kind of neat to see what hardware is connected at any given time, and watching what happens when I plug in various USB peripherals, etc.  I know, I have a severely deficient view of entertainment.  After amusing myself with this for about 5-10 minutes, I returned to my work.

Some time after this, I spotted out of the corner of my eye a Growl message that said 'Volume Mounted Google 8.0.0 (something)'  And just as quickly 'Volume Unmounted Google 8.0.0 (something)'.  I didn't get time for screen shots, it appeared and disappeared within seconds. 

Has anyone else noticed this and is the explanation for it posted somewhere online?  Apparently there's some helper process that's running that's doing it, but I don't see anything in Activity Monitor with Google or Chrome in the name.  I'm not a process-killing weenie, I'm just curious about this behavior I'd never noticed before.
Apparently there is a Google Software Update process that is queued to run periodically, which is why it's not always there. (I couldn't grab a screenshot of it, it was too sneaky). It's not just for Chrome, but for Google Earth and Picasa too. It was a bit of a breadcrumb hunt finding info about it.

I think the Google updater isn't a proces that runs all the time, but a launchd job that runs when you boot and every so often after that. Google com.google.keystone.user.agent and you'll find a number of explanations of what they've done (and how to get rid of it if you want).
charlie  (Apple Discussions)

From Google's Help Page:

Google Software Update is a background application for the Mac OS that helps ensure that you always have the most up-to-date, stable, and secure versions of the Google software you have installed. Google Software Update may run two services: GoogleSoftwareUpdateAgent and GoogleSoftwareUpdateDaemon. These services allow Google applications to be safely and securely updated.

I couldn't find, and I'm not aware of any reason it mounts a partition, but it's probably either:

A bunch of information about which updates are available and for what apps
Updates for products, Google Chrome updates are quite regular
An Update for the Updater

Ah the endless mysteries of HardwareGrowler. Entertainment for the whole family!