As in "Lock Widgets" from the desktop context menu? Or do you mean individual widgets?

Jason, I meant individual widgets, sorry for the abbreviation.

"lock this widget", "lock all widgets", "lock purple widgets"... blah. where will it end? how much is actually to be gained from this?

Aaron, who told anything about purple widgets? It is quite natural to have feature "enabled"/"disabled" for:
a) all items
b) this item
c) selected items

It is common UI for several years. KDE4 should not reinvent the wheel (especially the square one).

It's been decided to *not* lock individual widgets or even individual properties of individual widgets. The line has been drawn in that place. And it's quite sane, if you ask me. Anything else will probably be very confusing to users ...

I want to vote +1 for the possibility to lock plasmoids individually.

Here are my reasons why this is useful... I'm really missing this functionality!
1.) This would be equivalent to superkaramba widgets on KDE3, they can be locked individually. This is what users are used to.
2.) I want to lock some plasmoids, after I configured and positioned them, for ever (e.g. photo frames). But others, like Icons or Notes, I don't want to lock, because I move them much more often and they are not so big as photo frames, so it doesn't bother me if the option frame appears if I hover over them. But leaving big photo frames unlocked is really annoying, because of the option frame that appears when you accidentally hover over them.
3.) I like rotating photo frames slightly and let them overlap a bit, so that it looks like a pile of photos that was randomly thrown on my desktop. The problem is, that you have kind of trouble arranging the photos if you want them to overlap a bit, because you always interfere with the photos you've already positioned. If two plasmoids overlap a bit, both option frames are displayed when you hover with the mouse over the overlapping area. In this case it's not that easy to access the options of that frame you actually want to edit, because  the option frames of several widgets are active, overlap each other and interfere/hinder each other. If you could lock the photos individually, you could add the first photo, rotate and position it and lock it. Add the next one and rotate and position it (without triggering the option frame of the first one to appear) and lock it too. Add a 3rd photo... and so on... 
4. Take Note plasmoids on the other hand. They have a relatively short lifetime compared to photo frames. When I add a new Note with some information it lasts for a couple of hours and then I remove the Note plasmoid from my desktop. I don't really care for the exact position of the Note, it may temporarily overlap with other plasmoids (e.g. photo frames) and if it disturbs me where it currently is, I move it a bit. The point is, to move a Note or an Icon, I don't want to "Unlock All Widgets" first and trigger the option frames of the other widgets to appear, while I move the Note (or even rotate/scale/move the other widgets accidentally).

Altogether, I wanted to explain, that for me there are big differences between plasmoids and the functionality to lock widgets individually would be something I would highly appreciate. Maybe there are others who feel the same. Therefore I kindly request to reopen this feature request.

I propose too the ability to lock/unlock plasmoids, it *doesn't* hurt anyone, and it helpfull