Here's a detailed list of the changes in this firmware update:

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      Adds a user-selectable option to drop you back into whatever menu item you had last selected, vs. always taking you to the top of the menu system when you hit the Menu button. (A huge improvement in usability; one that frequently had us gnashing our teeth as we fiddled with the cameras many options while testing the prototypes.)
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      Adds a user-selectable option to make the NEX menus wrap so scrolling off the bottom will take you back to the top entry again. (Not quite as important as the first change above, but this still removes an enormous annoyance.)

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      Adds customizable buttons: A gigantic improvement for experienced users. The center button and lower-left button on the camera's back (see illustration above) can now have a wide range of camera functions assigned to them. Sony reps at the press event didn't have an exact number for how many functions could be assigned, but said it was "a whole passel" -- potentially 20 or more. Configurable options include things like white balance, ISO, exposure mode, etc. The center button can have up to three functions assigned to it simultaneously, which can be selected by pressing multiple times or pressing and scrolling with the rear control dial. The lower left button supports just one function at once. Bottom line, you'll be able to have up to four camera functions close at hand, rather than having to delve into the menu system.
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      Aperture control in Movie mode: Probably the biggest single request from video shooters, the new firmware will let you control the aperture used during video shooting in two different ways. In Auto mode, whatever amount of "background defocus" you select in still-image mode will apply to video recording as well. Likewise, if you've selected Aperture Priority mode for still shooting, the same aperture setting will apply when you switch to movie recording.
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      Support for A-mount Sony lenses with internal motors. Initially, the NEX cameras only supported the older A-mount lenses in manual focusing mode. The update will support autofocus operation with A-mount lenses that have internal focus motors. (We didn't take time to do a full count, but we think that's a total of about 12 lens models.) NOTE, though, that you actually have to upgrade the firmware in the lens adapter, as well as in the camera itself. (We were surprised to learn that the A-mount to E-mount adapter actually has a chip in it, to translate data between the lens and the camera body. As part of the update process, then, you'll need to attach your Sony A-mount adapter to the camera, so the camera can update the adapter's firmware.)