As reported on Jason Langridge's weblog here  O2 have released an update for the O2 Exec which includes AKU 2.0 and Direct Push features.
The update is labeled v1.30.162, following is a list of new & changed features:  

• Microsoft AKU 2 (Adaptation Kit Update) featuring:

  Microsoft Messaging and Security Feature Pack (MSFP) allowing Direct Push Email, Wireless Calendar, Contacts, Tasks, Global Address List (GAL) Lookup and Security Policies.

• Updated Comm Manager, providing new buttons for controlling Direct Push Mail and active Data connections.  
• Updated Radio v1.09.00  
• Updated CE image v1.30.107

The Update can be downloaded from here