Mark Wallace of 3pointd fame is a guest writer on Terra Nova.
This TN post is well worth reading, (though the extensive comments may get a bit much :-))
The base principle is one of meta guilds. This is something that we have explored in various ways. Eightbar exits in a few places including a very early presence in Eve-Online. We also have a wider team at IBM called the Virtual Universe Community. Our charter started out from our Second Life exploration but was always intended to cover multiple environments and places in the future so that we could work as one across many metaverses. Many of the meta guilds are clearly based around gameplay and more amusing concepts. Ours though is focussed on us as IBMers and as part of the industry.
To quote Mark
“A meta-guild — i.e., a guild with a presence across a number of virtual worlds and/or MMOs — allows a group to share their experiences of gameplay in various environments, and eases the process of traveling among such worlds for the individual.”