We are currently working in a private beta and so are still in the process of making fairly rapid changes, although obviously as usage is starting to ramp up, we will be slo
Appending the current time to the URL is indeed a common solution. However, you can also manage this at the web server level, if you want to. The server can be configured to send different HTTP headers for javascript files.
For example, to force the file to be cached for no longer than 1 day, you would send:
Cache-Control: max-age=86400, must-revalidate
For beta, if you want to force the user to always get the latest, you would use:
Cache-Control: no-cache, must-revalidate