Despite all the bits and pieces of information floating around, I have not been able to build a working OpenSim environment on a 64 bits CentOS server. Luckily I still have a 32 bits Linux rental too so I just reverted back to that environment, and got both my sims (the Open Grid beta sim and the standalone OpenSim which the kids use) back online in a snap.
OpenSim is doing fine these days, it's picking up steam as more parties begin to use it for serious stuff, as this post by Vint Falken shows.
But, the question on how the open grid will look like is not answered, and I think it won't be in quite some time.
One of the architectural directions that's being pursued, is the Open Grid Beta being done by Linden Labs with cooperation of the OpenSim dev team. The Open Grid beta is the result of the work of the Architecture Working Group, again a Linden sponsored effort. OGP has been successfully beta tested. In the Open Grid, you can teleport to any Open Grid enabled sim, provided that you know the address, but the current implementation does not support inventory yet. OGP is not only server side, there's also some client side work being done. In recent weeks it has been a bit quiet with OGP.
And then, there's this: The OpenSim HyperGrid, explained and discusses by Justincc here. It deals explicitly with inventory and looks to be server side only. One of the confusing things of Hyper Grid is, that world maps may change from region to region, as grid admins create their own grid maps. If you are in my region and you check the world map, you may see my region bordering on one from OSGrid. But if you teleport to that OSGrid region and then check the world map once you're there, you may never see mine! This allows for great flexibility but also for confusion.
Which one will it be, Hyper Grid or OGP? I'm not sure and I don't think anyone is. Perhaps we'll end up with a bit of both as they both have their strong sides. Hyper Grid has some issues to solve regarding protection of copyrights for objects in inventory, but it looks like the most 'open' solution. OGP is backed by Linden Labs and may in the future give access to Linden Labs owned grids, which is definitely interesting, but inventory hasn't been dealt with at all at this moment.
I tried to Hyper Grid enable by Open Grid Beta sim yesterday. that wouldn't work due to configuration issues, but I am certainly going to try again. Wouldn't that be interesting, a OpenSim that is both HyperGridded and OGP enabled?