Apple are today seeding registered members of the Mac Developer Program the latest, third developer preview of OS X Mountain Lion. The new version is Build 12A178q, which is up from the previous 12A154q version.

There are various changes baked in which have yet to be discovered, but the lucky ones with access to the Developer Preview will surely swim through the sea of changes to find out just how Mountain Lion ticks, or roars. Apple has a list of known issues with the latest build:

- On systems with FileVault enabled, canceling the restart to the Mountain Lion Developer Preview 3 Installer may leave your system unable to present a password dialog at boot time. You can repair the problem by holding down command-R to boot to the Recovery OS and then using Disk Utility to unlock and Repair your volume.

- Installing OS X 10.8 over 10.7.2 or earlier with FileVault turned on may fail

- Pre-Lion FileVault user accounts are not supported in this Developer Preview

- Some Apple menu items such as Restart may not work when a sandboxed app is in the foreground

- iTunes no longer syncs Notes

- Mail's photo browser cannot access the iPhoto library

- Back to My Mac doesn't work for the first 5 minutes after rebooting

- DVD Player may not launch after inserting a DVD on some systems

- Most help topics are unavailable in this Developer Preview

- In the Recovery HD:

- Some icons may be missing

- Network Utility's Lookup pane does not work

- Time Machine restoration via a AFP share does not work

- Restoring from a Time Machine backup via AFP does not work

- Migration from a Time Machine backup that excludes paths such as /System may yield an unusable system

- Brightness settings may change unexpectedly after reboot

- Display brightness may be dim after sleep or reboot

- If Mail is hidden at logout time, it may not be correctly relaunched during a subsequent login but will appear to be running

- Java applets may not work in Safari

- QuickTime screen recordings may produce corrupted videos or cause an exception when run on machines with NVDIA graphics

Apple seem to be putting a fair amount of time into getting Game Center up and running on the latest iteration of OS X in this build. Mountain Lion is scheduled for release in "late summer".