The current Mac OS is Lion, version 10.7. LightSpeed 3.6, available now, offers full Lion compatibility in addition to powerful new features to help store owners grow their retail businesses.
Versions of LightSpeed previous to 3.5 are not compatible with Lion, and installing Lion on a LightSpeed Server that is not running version 3.5 or higher may result in loss of functionality and potential data loss. Below are important instructions on how to prepare your LightSpeed installation for Lion.
Please Note: In order to upgrade to LightSpeed 3.6, you must have a Support & Upgrades Subscription that was valid on November 1, 2011. Please visit our Store page, contact your local LightSpeed reseller or contact LightSpeed Sales to process a renewal if your subscription has expired.

It is important that you follow the following steps to properly upgrade your LightSpeed Server to Mac OS X Lion and LightSpeed 3.6:
Please note that LightSpeed 3.6 has the following new requirements:
In order to support Lion (10.7), LightSpeed 3.6 is not supported on computers running Mac OS X Leopard (10.5) or PowerPC-based Macs.
LightSpeed 3.6 requires you to update to LightSpeed Mobile 1.6 on your iPhone or iPod touch, and is a free download via iTunes. This version adds line-item editing of quantities, discounts and product descriptions.
If you are not upgrading to LightSpeed 3.6 do not upgrade to LightSpeed Mobile 1.6, as it will not connect to earlier versions of LightSpeed Server.
Do not install the LightSpeed 3.6 Demo on a production LightSpeed Server running LightSpeed 3.4.x or older, as the upgraded System Preferences panel will not work with older versions of LightSpeed and you will not be able to administrate your server.