Looking at the Mesh Upload Enablement test-plan on the Second Life Wiki (created today as Scobu Linden’s first Wiki contribution), it appears as if the ability to upload mesh content is going to be restricted on a per-user basis, independent of any other factor. For most users, to earn that ability initially, you’re going to need payment information on file, and go through a tutorial.
Having passed these two hurdles, you get your Mesh Enablement bit; a license to upload arbitrary mesh objects, if you prefer to think of it that way.
The Lab, however, seems able to revoke that license if they feel the need, at which point Second Life will no longer allow your account to upload arbitrary mesh objects, without otherwise affecting any other Second Life permissions you might have.
Now, on one hand I can think of a number of content-creator/merchants who traditionally have always had freebie accounts who would definitely be affected by this. They’d have to get payment information on file or be unable to upload arbitrary mesh objects, period.
On the other hand, I can see the Lab needing some protection here. Meshes can be pulled out of pretty much any PC or console game, with more or less work. Some are already in the COLLADA (COLLAborative Design Activity) format that you’d need to upload them into Second Life.
A large part of the Lab’s covering its collective arse legally – if you should start uploading piles of assets from Crysis 2, or Fallout: New Vegas – would be in being able to identify you to an angry publisher.
Clearly, the Lab sees and recognises the potential for sticky issues with mesh and is gating that ability, while keeping a hand on the gate. Balancing the two interests is going to be tricky, though.