Try as we might, a few annoying bugs slipped in to the 1.40 release. Rather than wait till the next scheduled release to fix them, we’re releasing a minor update to correct the issues. You can get it now from the download page.
The primary issues fixed in this release include:

• Cancel not working or giving odd behavior for background uploads
• Directory caching preventing changes made on one machine from showing up on another
• Timeout during copy / rename of large files using fast file copy

You can see the full details in the release notes.

A quick note on using Jungle Disk to share files between multiple machines. The default cache settings in Jungle Disk make it so that changes made on one machine will not likely show up on another machine for 2-3 minutes. Furthermore, Mac Finder has its own caching and in some cases you may need to remount the volume (using the Jungle Disk menu option) in order for new files to appear. If you want changes to show up faster, you can modify the CacheCheckInterval setting in the jungledisk-settings.ini file (currently this setting is not available in the configuration UI). Simply change the value (in seconds) to reduce the length of time that Jungle Disk waits to check for changes to cached data.