Windows Mobile 5.0のAKUによる違いは？：msmobiles.com

WM5 PDA

Not all Windows Mobile 5.0 operating systems are equal! The main difference lies in which AKU given Windows Mobile device has in its ROM image. Here we explain in big details and with many screen shots what is in AKU 3 and also in some older AKUs (older AKUs are included in new ones too). This information is vital particularly when you are buying new phone and you would like to get some specific thing from some specific AKU...

msmobiles.com にWindows Mobile 5.0は全てにおいて同じではなく、AKU(Adaptation Kit Update)という細かいバージョンによって機能が違うという解説が掲載されています！
最新版はAKU3.3などがあるそうですがU-SIMの操作を含む3Gへの対応強化、言語パック、インターネット共有、設定ウィザード、WiFiなどかなりの点で変わっています。

  • 3G Feature Pack
    • Integrated SIM/USIM Contacts Experience
    • Sorting Contacts Alphabetically
    • USIM / SIM Contacts POOM Improvements
    • 3G Network Control Panel Updates
    • Shell Improvements
    • Video Telephony
    • Sample UMTS RIL
  • Language Pack Installation
    • Language Pack Installation for Pocket PC
  • Auxiliary Display Support
  • Internet Sharing
    • Internet Sharing including Bluetooth PAN Profile
  • Quick Start Wizard
  • Email Account Setup Wizard
  • ActiveSync
    • Billing Support for Mobile Operators (AKU2.6)
    • RNDIS and Serial Switching support (AKU2.3)
    • Improved Serial Connectivity Performance
  • Wi-Fi Feature Pack and Connectivity
    • Wi-Fi Wireless Protected Access (WPA) 2 Support
    • SP Wi-Fi New Connection wizard
    • PPC Wi-Fi One Handed Navigation Improvements
    • PPC Wi-Fi card improvements for connection enumerations
  • Wi-Fi and Connectivity
    • Pocket PC Better Display Wi-Fi and Cellular Connection Status (2.3)
    • Wi-Fi Quality of Service (QOS) improvements
    • Wireless Manager Disconnect Cellular Data option
    • Bluetooth Visible Settings
  • Messaging
    • Pre-provisioned Email Accounts
    • Send V-Card over SMS
    • SMS Multiple Recipient Improvements
    • Save SMS to SIM
    • Pocket PC Folder Selection
    • SMS over GPRS
  • Windows Media Player
    • Video Scaling
    • Save Play List Support
    • Equalizer
    • Search
  • Shell
    • PPC SIM PIN Counter
    • Sending of Separate Delivery OMA DRM V1 Content
    • Jog Dial Support for PPC and SP (AKU1.3)
    • Advanced Audio Distribution Profile (A2DP)
    • Home Screen Smart Filtering Improvements for SP (AKU 2.5)
    • Smartphone Dynamic Rotation Support for QVGA devices (AKU2.1)
    • Customization of PPC Dialer Colors (AKU2.5)
  • Applications
    • Voice Command
    • Internet Explorer Mobile Improvements
    • Camera
    • .NET CF V2
    • OEM and Operator Bug Fixes

AKUのバージョンを確かめるなら、日本語版のデバイスなら「スタート」メニュー→「設定」→「システム」タブ→「バージョン情報」→「バージョン」タブ、英語版なら「Start」メニュー→「Settings」→「System」タブ→「About」→「Version」タブににある2行目末尾の数字がAKUのバージョンです。
例： OS 5.1.195(Build 1489.2.6.0) であれば2.6.0がAKUのバージョンとなりAKU2.6と言えます。
http://msmobiles.com/news.php/5857.html