Haven't seen any mention about that either, I've been looking at A mount lenses for more versatility but was rather alarmed by the decrease in focus speed with these lenses. Below is the full press release from Sony about the firmware update, last paragraph mentions the autofocus speed reduction:
FURTHER ENHANCEMENTS FOR SONY NEX-5 AND NEX-3 CAMERAS
Firmware upgrade adds AF support for A-mount lenses
A new firmware upgrade adds further operating refinements to the NEX-5 and NEX-3 compact system cameras from Sony.
Available now for download1 with versions available for Windows and Mac OS2, the free upgrade adds several performance enhancements. Autofocus is now supported when using the NEX-5 and NEX-3 with 14 lenses from the full range of A-mount optics by Sony and Carl Zeiss that includes telephotos, primes and zooms. Aperture settings can be maintained during HD movie recording, and system menu operation has been streamlined alongside other usability improvements. Registered NEX-5/NEX-3 owners will be advised of the free update via email.
Autofocus with A-mount lenses
Single-shot autofocus is supported with 14 optional A-mount SAM and SSM lens models3 when used with the optional LA-EA1 Mount Adaptor. Single-shot AF is also possible while in movie recording mode by pressing the shutter button halfway down. Support for AF operation with A-mount lenses also requires a separate firmware upgrade for the LA-EA1.
Aperture priority with video recording
HD video can be shot while maintaining constant aperture, either in A (aperture priority) mode or in iAuto mode with background defocus activated. This aids the simple creation of beautiful background defocus effects during movie recording.
Soft key settings
It's possible to customise functions of two of the three soft keys on the camera's rear panel. Functions that can be assigned include Shooting Mode, Shooting Tips, Precision Digital Zoom, ISO, White Balance, Metering Mode, Flash Compensation, DRO, Auto HDR, Creative Style, MF Assist and AF Area.
When 'Menu' is selected, there is now the option to display either the main menu screen or the last parameter set. This simplifies quick readjustment of recently-selected functions and settings.
An enlarged image portion can be displayed on screen with user-selectable duration while in MF (Manual Focus) Assist mode. MF Assist operation has also been improved. The previously-chosen magnified image portion can now be maintained when MF Assist is re-selected, making repeated checks of fine focus quicker and more convenient.
Notes to editors
1 NEX-5/NEX-3 customers can download the firmware upgrade from http://support.sony-europe.com/hub/hub.html
2 System requirements [PC]: Windows XP SP3 (64-bit and Starter editions not supported); Windows Vista SP2 (Starter edition not supported); Windows 7
System requirements [Macintosh]: OS X (Ver.10.5 and Ver.10.6).
[PC/Mac] Hard disk space: min. 200MB / RAM: min. 512MB.
Upgrade requires USB cable connection between computer and NEX-5/NEX-3.
3 Autofocus function is supported with these A-mount lenses:
· DT 18-55mm F3.5-5.6 SAM [SAL1855]
· 28-75mm F2.8 SAM [SAL2875],
· DT 55-200mm F4-5.6 SAM [SAL55200-2]
· DT 30mm F2.8 Macro SAM [SAL30M28]
· DT 35mm F1.8 SAM [SAL35F18]
· DT 50mm F1.8 SAM [SAL50F18]
· 85mm F2.8 SAM [SAL85F28]
· Vario-Sonnar T* 16-35mm F2.8 ZA SSM [SAL1635Z]
· Vario-Sonnar T* 24-70mm F2.8 ZA SSM [SAL2470Z]
· Distagon T* 24mm F2 ZA SSM [SAL24F20Z]
· 70-200mm F2.8 G [SAL70200G]
· 70-300mm F4.5-5.6 G SSM [SAL70300G]
· 70-400mm F4-5.6 G SSM [SAL70400G]
· 300mm F2.8 G [SAL300F28G]
AF support also requires firmware upgrade for optional LA-EA1 Lens Mount Adaptor.
With an A-mount lens attached to NEX-5/NEX-3, autofocus takes approximately 2 to 7 seconds based on Sony measurement standards. Actual AF time with A-mount lens may vary depending on the subject and shooting conditions.