If you are running OS X Lion/Mountain Lion and attempting to validate and activate Pitch 'n Time LE in the Audio Units manager in Logic Pro, you may receive a "crashed validation" result. This is something we are investigating currently but shouldn't cause you any problems.
If you ignore this error and click "done", you should still then be able to activate the plug-in and select Pitch 'n Time as an algorithm in Logic's Time and Pitch Machine and it should function as normal.
This issue may also appear in the form of an error message "You are using incompatible Audio Units" when starting Logic Pro. Clicking Ignore should allow Pitch 'n Time to still be enabled in the Audio Units manager and it should work fine.
If you are still having trouble getting Pitch 'n Time LE to work, please start a help request here