There are a lot of people anxiously awaiting the arrival of mesh importing on SL. They think it'll be neat stuff and make the world a better, richer, more interesting place. I think it's dead on arrival.
For those of you who don't know what that is (yes, there are probably some yet), meshes are a way to build objects with any shape desired in a 3D modeling program like Maya or Blender and have them appear in SL just as they were designed. A mesh describes an object as a series of vertices, with lines and surfaces connecting them. Any object can be modeled this way; how well is a matter of how many vertices are used.
SL has actually had a form of meshes for quite some time. A sculpt is a mesh, but limited in the level of detail by the fact that it can have at most 1024 vertices. That's enough for quite a lot of creativity, but it's not enough for many things. Sculpts are usually used to make one part of a larger item, in greater detail than can be done just with primitive objects like boxes and spheres and cylinders.
A mesh doesn't have that limitation. One demonstration I've seen is of an Audi R8 in one 8192-vertex mesh. It looked quite impressive. That's the kind of eye candy that Linden Lab is hoping creators will make, and that users will demand. People have been demanding it for years and eagerly awaiting it ever since LL announced they'd do it.
There's only one problem: Mesh is dead on arrival. As currently planned, it's got far too many things wrong with it to be useful to content creators.
The first hurdle is that it requires massive changes to the viewer's scene rendering code (the part of the viewer that draws the picture shown on your computer screen). These changes, practically speaking, are only practical in LL's Viewer 2 or third party viewers based on it. This runs smack dab head-on into the basic fact that the SL user community hates the Viewer 2 user interface with a passion normally reserved for a kid hating Brussels sprouts. LL's been trying hard to get users to Viewer 2 ever since it was introduced early this year. The latest figure I've heard is that it's now used for 20% of logins to SL. Where are the users? Either still on 1.23 (which Viewer 2 just passed in popularity for the first time last week), or else third party viewers. Before Emeraldgate, Emerald had 60% of the userbase all by itself. Since then, the users have scattered, with most moving to Phoenix, but a large number are using Imprudence, Emergence (which is deprecated by the developer, who recommends that people use Phoenix instead), and Ascent. All of those are based on the version 1 codebase, which will not show meshes.
All of that means there's a chicken and egg problem. Content creators aren't going to bother with meshes unless there's significant demand, and a significant number of users who can actually see the content they'll create. Users aren't going to switch to Viewer 2 just for meshes that aren't being created, no matter how much LL might think otherwise. Oz Linden said that he expected mesh to drive users to Viewer 2 at a recent third party viewer developer meeting. I think he's full of prunes. That's wishful thinking. Mesh won't overcome users' hatred for the Viewer 2 user interface.
There's another problem with meshes for content creators: Oskar Linden announced at yesterday's mesh office hour that no third-party viewer would be permitted to use LL's mesh upload code in their viewer. It seems that the upload code uses part of the Havok physics library that LL licenses from Intel. That library is very much not open source, and LL is not permitted to distribute it except as part of their own program. This means that a content creator will have to exit his viewer of choice (almost none of them are using Viewer 2, because they can't afford to take the weeks needed to become proficient in the UI), start up Viewer 2, upload the mesh, then sign out and back in with his regular viewer. To a big content creator, time is money. If using a mesh takes up that much time and effort, they just won't bother.
Meshes are also considerably less useful than they might appear to be to clothing designers, because they cannot be made flexible. A piece of rigid clothing isn't very comfortable or realistic.
Finally, the cost of using meshes, as things currently stand, is astronomical. There are only two things in SL that cost real money: land area and primitive usage. That's because both translate directly into load on the server computers that run Second Life. Meshes also add to that load, so they need to count as well. Just how much they cost isn't known outside the group within LL that is doing the project (and maybe by nobody, really, but Andrew Linden). This cost is being expressed as an equivalent number of primitives, and will count against the primitive limit for a parcel of land. The problem is that that cost is being set high enough that, in many cases, a mesh object is more expensive than the same object built up out of primitives. Yes, the mesh object looks a little bit nicer, but if the price is double that of the primitive-based object, why bother?
As I said above, Linden Lab has a chicken-and-egg problem with mesh. The rest of the problems with it pretty much guarantee that people aren't going to make the leaps needed to exploit them. Despite LL's best hopes for meshes pushing people to Viewer 2, it just ain't gonna work that way. Mesh is dead on arrival.