I could see the Church doing something such as:
- Chat with missionaries (investigators can already chat online with missionaries at the MTC -- http://mormon.org/question/0,8534,795-1,00.html) This doesn't seem like a significant stretch from this.
- Virtual museum gallery of historical or art (similar to what is housed physically at the Museum of Church History and Art west of Temple Square)
- See / hear a virtual concert -- it may be a live broadcast on radio or tv (or prerecorded) of the Mormon Tabernacle Choir, an organ recital, or some other cultural event
- Attend a virtual fireside (LDS teens could socialize with others with their same values from around the world)
- See a virtual presentation similar to ones at visitor centers near many temples
There are a whole host of challenges and concerns which would need to be addressed before this could happen... but it isn't something that should be discounted.
I envision a virtual "Temple Square" in Second Life ("SL") complete with all of the landscaping and buildings. The more detail the better (well, except the SL Salt Lake Temple itself, which could just be one big 100' tall room on the inside). The roaming missionary avatars that would populate the area could do exactly what they do now at Temple Square ("Hi, can I answer any questions you have?").
The missionary possibilities of SL are extremely attractive because there are no geopolitical boundaries inside of SL. Therefore, a citizen of China who may not be able to take the lessons from missionaries in his or her home could instead visit the virtual Temple Square inside of SL and learn about the Restoration from the on-line missionary avatars, get a virtual copy of the Book of Mormon, etc.
To drive people to the virtual site, there would have to be some giveaways or freebies. Since Temple Square is renowned for its gardens, then they could possibly make all of the bushes, tree, flowers, walkways, paths, water features, statues, furniture, decorative items, doors, windows, wall textures, etc that they will have to create in order to build the virtual Temple Square as the freebies that they give away, e.g. "click on this crate for 50 types of bulb flowers", or "click on this crate for 25 types of flowering trees", etc. In the wintertime, you can add some giveaways for the prims in a manger scene, and another for different kinds of Christmas lights. The possibilities are literally endless. Also, include in each "crate of goodies" a note that would include an official message from the LDS Church. The note may include some scripture, instructions on how to get more information, a link to teleport back to the SL Temple Square, or all of the above.
Furthermore, it is possible to write and attach scripts to make objects perform different tasks (like, for example, tulips to open when the sun is shining and close when it is not), so the more clever the objects that are given away the more appeal they will have... and thus the more people will want to own it - driving more traffic to the SL Temple Square. Make the objects non-copyable so that everyone must get it from the source... i.e. where all of the virtual missionaries are.
You can also set up guided tours of any virtual landscape in SL, for example... see what has been done on the island of Svarga, where a complete ecology runs autonomously (including clouds, rain, sunshine, bees, birds, trees and flowers). On Svarga, there are little "hover discs" that will take anyone who sits on one around the island and explain different aspects of the virtual site. It would be trivial to re-create the same functionality at a virtual Temple Square inside of Second Life.
Actually, if you make the SL Temple Square picturesque enough. People will just show up at the Virtual Temple Square to have their virtual picture taken at the site... just like people do in the RL Temple Square.
Anyway. It would be cool to get in now while there is still press spotlight to be had for companies and organizations that are joining in. It could be a huge.