Elastic Load Balancing enables you to balance incoming requests between an array of EC2 instances. ELB supports SSL termination and sticky http/https sessions. The most reliable way to enable sticky sessions with WO is to store session id's in cookies, then choose "application server generated cookies" as your preferred method for sticky sessions and have the ELB monitor your wosid cookie.
You can get more information about Amazon EC2 in the presentation Ubermind made about it at WOWODC West 2009.
In a post to the WebObjects development mailing list in February 2011, Joe Kramer from Übermind notes that "WOlastic is no longer supported by Ubermind." From the engineer behind WOlastic:
Also see See Deploying via Chef.