As the number of virtual environments increases, standards and vendor collaboration will help make teleporting between different worlds a smooth experience, ensuring, for instance, that your avatar arrives in a new world still wearing the clothes it donned in your home world.

Currently, Linden Research Inc.'s Second Life is the most popular virtual world, outshining a number of alternative universes such as Active Worlds and There.

"A lot of people are looking at Second Life and saying, 'Let's do one of those,'" said Bob Sutor, vice president of standards and open source at IBM Corp. "The last thing you want is a lot of different ways to do the same things. You need standards for how to teleport between different virtual worlds and to bring objects with you."

Besides an avatar's clothes, those objects could include the money it was using in your home virtual world as well as a presentation you might want to share with your colleagues or potential customers.

Issues to consider include the mechanics of teleporting between worlds, Sutor said. If you invite someone from another world to come and visit your world, would they need to become a member of your environment or could you simply issue a guest pass? Can a person retain their home world identity in a new world? He also wondered how people will communicate across worlds, for example, via IM (instant messaging). That could be achieved by agreeing on a common service or setting up gateways between different IM systems.

IBM's set to debate these issues on Friday at a virtual worlds event it's cohosting with the Massachusetts Institute of Technology at the MIT Media Lab in Cambridge. Sutor will be there along with Mitch Kapor, the chair of Linden Lab, and a variety of academics and companies including Toyota Motor Sales USA Inc. and PepsiCo Inc.

Sutor applauded Second Life's move in January to make the source code for its end-user viewer application freely available. The viewer enables users to do a variety of things in the virtual world, including controlling avatars, communicating and buying and selling objects.

"They've set a very interesting precedent," he said. Sutor expects that other virtual worlds will follow suit. Like the open-source movement, "virtual worlds are fundamentally about communities coming together," he added, looking forward to the establishment of a global community of developers focused on building worlds based on open standards.

Sutor has been using Second Life actively since November and has been detailing in recent blog postings his virtual world requirements . That's a common experience for users once they've adjusted to moving around in a virtual world, he believes.

"After they've finished walking into walls, they probably say, 'This is OK, but I really wish it did X, Y or Z'," Sutor said. "The odds are other virtual worlds have that. Looked at in total, we probably have much of what people would like implemented already available somewhere." For example, World of Warcraft, a hugely popular multiplayer online role-playing game, has many features that could be applied in other virtual worlds, he added.

Businesses are experimenting with virtual worlds, particularly inside Second Life. "They're mostly translating 2-D marketing ideas into a 3-D world, which is more or less successful," Sutor said. But looking ahead, questions arise around the meaning of the retail experience in a virtual world.

For instance, what kind of artificial intelligence will companies use to determine how sales assistants in virtual stores behave when a customer walks in? Will the customer be approached by the sales assistant closest to them or by the assistant who looks the most like them, Sutor wondered. Alternatively, will the sales assistants be programmed to examine the customer's avatar to determine what you're likely to purchase and therefore which assistant could be of the most help to you?