Export list of activesync devices

For a single user you can run

Get-ActiveSyncDeviceStatistics -Mailbox "John Smith" | Select-Object @{n="Mailbox";e={$mailbox}}, LastSuccessSync, Status, DeviceID, DeviceType, DeviceUserAgent, DeviceModel, DeviceIMEI, DeviceOS

For all users you can run

Set-AdServerSettings -ViewEntireForest $True
Function New-Array {,$args}
$Report = new-array
$file_out = "C:\temp\mobile_devices.csv"
$mbx = Get-CASMailbox -ResultSize Unlimited | ?{$_.HasActiveSyncDevicePartnership}
$mbx | ForEach-Object {
 $mailbox = $_.Name
$PrimarySMTPAddress = $([string]$_.PrimarySMTPAddress)
 $stats = Get-ActiveSyncDeviceStatistics -Mailbox $PrimarySMTPAddress
 if($stats){
  foreach ($dev in $stats){
   $device = New-Object System.Object
   $device | Add-Member -type NoteProperty -name Mailbox -value $mailbox
   $device | Add-Member -type NoteProperty -name LastSuccessSync -value $dev.LastSuccessSync
   $device | Add-Member -type NoteProperty -name DeviceID -value $([string]$dev.DeviceID)
   $device | Add-Member -type NoteProperty -name DeviceType -value $dev.DeviceType
   $device | Add-Member -type NoteProperty -name DeviceUserAgent -value $dev.DeviceUserAgent
   $device | Add-Member -type NoteProperty -name DeviceModel -value $dev.DeviceModel
   $device | Add-Member -type NoteProperty -name DeviceIMEI -value $([string]$dev.DeviceIMEI)
   $device | Add-Member -type NoteProperty -name DeviceOS -value $dev.DeviceOS
   $Report += $device
  }
 }
}
$Report | Export-Csv $file_out -NoType

Credit to: http://exchangeblog.pl/en/2012/10/exchange-2010-activesync-devices-list/