As officially posted in the Linden blog here starting from August 23rd with the possible exception of some minor testing channel, now SecondLife has mesh support worldwide.
This means that you can have sophisticated content soon to be shown off in-world. As usual in SecondLife this interests two categories of people: those who will produce mesh content and those who will simply enjoy new creations.
For Content Creators
If you are a builder, fashion creative and want to produce your own goods, you must learn how to master 3D standard tools like Maya, Blender, 3D max to produce a collada “.dae” file to be uploaded to the grid. Differently from “old” sculpties to be able to complete the upload you must either have PIOF (Pay Information on file, meaning you provided a credit card to Linden to legally identify you) and pass a test to get a “license to upload” specifying you knows about IP (Intellectual Property copyrights) and are not going to infringe them. To check and attend the “examination” you must login on secondlife.com and go here. You must also be sure to have either official Linden Viewer or Kirstens S21(9). In the future Firestorm (and maybe Phoenix) will probably allow to upload meshes. My best advice for content creators would be to use Blender and check this website http://machinimatrix.org and in particular the following two youtube playlists from Gaia Clary: the kettle quest or the shoe quest. Official Linden Page dedicated to mesh is here:
For everybody who wants to Enjoy Meshes
If you simply want to enjoy meshes and avoid seeing strange things like this (this is how it is seen with non mesh enabled viewer such as Phoenix):
- and you would rather prefer seeing better things like this:
- How it appears with a mesh enabled viewer
you should either get the official viewers from Linden (or Kirstens S21), as before, but if it happens that you don’t like the viewer 2/3 evolution, you can use Singularity viewer (which is in the TPVP listing of allowed browsers), I’m currently using a preview version of Singularity named Astra produced by Latif Khalifa downloadable for Windows here. This version should go public very soon.
The avatar you see has been created by Salvatore La Bua which is also selling it on the SLMarketplace here. or inworld here (it is cheaper buying inworld because of LL fees).
Here is a couple of youtube presentation of this avatar:
http://www.youtube.com/watch?v=Bi8eeSnFPX0 or http://www.youtube.com/watch?v=YXhQCui7nHA
If any creator does want to try his hands on producing such kind of “rigged avatars” or “rigged clothes” can follow the incredible tutorial found here: http://community.secondlife.com/t5/Mesh/Second-Life-Rigged-Clothing-Tutorial-Series-Blender/m-p/1027925#M4848
And the “adult parts”
I feel that new meshes will produce in the medium future a revolution in the way we perceive avatars. Until now LL gave us male (or female) avatars without genitalia, but this limitation now can be overriden. And people can be much more confident with a virtual body without menomations… 
I asked to Salvatore on google plus some info about this, and here is the answer:
Thank you
This means that you still need to do some complex tricks for actual “acting” of genitalia, but is still a step forward to 3D completeness…
Salahzar Stenvaag
I was contacted by Salvatore La Bua who suggested me to have the best results I should wear a Female shape. I did that and set all parameters to 50 as suggested and results were quite more enjoyable. This is also something interesting: to look well in Meshes you must not have a defined or obvious sexual identity