In an apparent split at the top, one of Second Life's founding employees has left the company, and his former boss apparently bids him a heartfelt good riddance.

Linden Labs CTO Cory Ondrejka, the fourth employee to be hired by the producer of the Second Life virtual world, left the company this week -- apparently at the decision of his boss Philip Rosedale, who publicly signaled his desire for completion of a new user interface as well as his unhappiness over the site's frequent crashes as early as late November.

In an internal memo obtained by an external blogger, Ondrejka told other former fellow employees this week that Linden Lab founder and CEO Rosedale's visions for the future were different enough from his own that Rosedale has now "decided to lead in his own way."

"I continue to believe in both Second Life and Linden Lab, but Philip and my visions for the future of Linden Lab are divergent enough that he decided to lead in his own way," Ondrejka wrote, in an internal memo posted by blogger Moo Money.

Ondrejka's e-mail came in response to an earlier internal memo by Rosedale, who told Second Life's employees that he and Linden have been experiencing "differences in how we think Linden should be run, differences that in the past few months have become irreconcilable."

Also according to Rosedale: "I feel that we need a different set of strengths in engineering leadership."

At the same time, Rosedale credited Linden with being "a huge part of of the company, having designed big part of [Second Life], hired many people, contributed greatly to the culture, and given a powerful voice to SL and [Linden Lab]."

But Rosedale actually started hinting at his displeasure over engineering issues as early as late November, when he used his blog on Second Life to signal a change in direction for the company -- away from frequent site crashes and toward a new user interface, for example.

"Our weakest link is now clearly crashing (both client and server), and we are going to very substantially reduce it over the next two quarters," Rosedale told members of the Second Life community.

"We aren't there yet in terms of the interface for virtual worlds. There is now a small new internal team doing nothing else, so expect real progress."

In other Web postings over the past year, Second Life staff has been warning users of impending shutdowns, and users have been complaining -- sometimes bitterly -- to Linden Lab as well as among themselves.

On the user interface side, Second Life acquired WindLight last spring, with plans to integrate its atmospheric and cloud simulation technologies into the client-side Second Life Viewer, and of open-sourcing the code.

Clearly, some of the obvious tensions between Rosedale and Ondrejka spring from competitve pressures surrounding the rapid growth of virtual communities on the Web.

These tensions "were more manageable when we were smaller, and there have been times that they have helped us do great work together," Rosedale wrote in his internal memo.

According to industry analysts at the Gartner Group, five years from now, as many as 80% of active Internet users -- amounting to 250 million people -- will be participating in virtual worlds.

Meanwhile, although Second Life is the dominant virtual world on the Web, with some 11 million members, it is hardly the only virtual world around. Up-and-comer Kaneva, for example, now claims membership of at least 800,000 visitors.