Last friday, at the office hour on aditi, Periapse Linden told us that Qarl Linden is working in this direction.

Periapse Linden: "Qarl tends to do these little things that produce grid changing results. Sculpties, uv picking, and now the invisiprim solution"

Personally I was thinking along the lines of numbering each face strategicly, using bitfields for different bodyparts.
Then it should be possible to turn each face on or off individually, or as a range. In most applications the masking could be done with just a handfull of integers.

I'm sure what's cooking in Qarl's kitchen will be very tasty though

However this has my support even implemented as described, as it's fairly simple but allows us to remove all the common problem areas (or the whole avatar!)

[edit]
Just noticed your mention of the "Baby Ruth" thing if all parts are hidden; I don't believe anything should be rendered if all items are unchecked, unless display transparent is turned on (in which case all missing pieces would be rendered in red so the location of the avatar is known). My main reason for posting VWR-812 is that I've made a full-prim avatar that unfortunately can't be made slimmer due to the base avatar underneath which is quite annoying, so I want nothing left-over to hide =)

Avatar mesh polygons for the eliminated portions would not exist. This would be a truncation of the mesh, not a transparent layer. I don't have a photo of the effect I'm talking about, but when mirrors actually worked you could look at the reflection of your avatar in mouselook and see your head completely pinched off. The same thing would apply here: if you remove the foot using this tool your leg would pinch off at the ankle.

Hiding the base avatar completely: I don't care, I don't have a problem with that. Other people do, and what was actually implemented would be up to Linden Labs in any case.

This is an option that would let you to tell SL not to produce your avatar mesh, or parts of the avatar mesh, at all. The avatar mesh would then not be visible to anyone; it would not be drawn at all.

The grand niftiness of this is that, unlike many other good ideas, it should actually REDUCE the work of the servers and the client, by eliminating stuff that servers and client now have to to deal with!!!

If it is too hard at present to make each body part disappear individually, it should still be possible to have a single button in Appearance. Click "No Appearance" and, poof, your avatar disappears from view. Simple.

This is a very important idea and would revolutionize avatar design. I have many abstract and artistic avatar designs in mind that I simply cannot do at present. I am sure that this option would produce a surge of avatar creativity and quality. Imagine, for example, what Flea Bussy and Psyra Extrordinaire would do if they could attach creations to avatars without the avatars having to be visualized or else hidden with stupid flaky interfering invisiprims. It is completely win win. This MUST be done.

The only problem I can see is if the mesh is replaced by a 'Ruthcloud'.... this shouldn't happen, IMO. if you wanted a small av, or one with seethrough parts, why should you have to cover the cloud?

Also, bringing back the Primitar should mean at least slightly less work, since the code may still be hanging around.

On the other hand, being able to apply a translucent skin to an av and render it seethrough (to the alpha level of the texture, hidden completely if totally clear) would probably be the most flexible way to do things, allowing for the most avatar customization. The tradeoff, however, is it would likely mean completely redoing the way skins are handled.