using Maybankard2 AMEX with AirAsia and Malaysia Airlines - transaction date posted @ M2U is same as date i make the payment.
all transaction on Sat/Sun so far from both websites got cashback, even the transaction is not in RM (converted), example buy AA from Medan-KL

will post transaction on non-malaysian website after this ~
Added on October 11, 2011, 3:26 pmCard Used : MAYBANKARD 2 AMEX
Website : CLEVERBRIDGE AG KOELN 27 (Prevx Security Software, who want to buy, can buy from me, using my id less 5%

)
User Transaction Date & Time : Thursday, 15 September, 7:46 PM
Website Transaction Date & Time : Thursday, 15 September, 7:46 PM
Transaction Posted on Maybank2u : 15-Sep-2011 (same day!)
Currency transacted / Posted : $1 -> MYR3.189
Cash Back Earned : Not getting it since on weekdays (purchase for cust)
Added on October 11, 2011, 3:38 pmCard Used : MAYBANKARD 2 AMEX
Website : YAHOO US
User Transaction Date & Time : Sunday, 2 October, 8:14 AM
Website Transaction Date & Time : Sunday, 2 October, 8:14 AM
Transaction Posted on Maybank2u : 1-Oct-2011 (Saturday. Follows US time probably. Should get cashback later)
Currency transacted / Posted : $1 -> MYR3.2734
Cash Back Earned : Not getting it yet, wait next month

Added on October 11, 2011, 4:09 pmCard Used : MAYBANKARD 2 AMEX
Website : 2CHECKOUT.COM COLUMBUS US - this is payment gateway (also known as 2CO) like PayPal
User Transaction Date & Time : Friday, 7 October, 6:17 AM
Website Transaction Date & Time : Friday, 7 October, 6:17 AM
Transaction Posted on Maybank2u : 8-Oct-2011 (Saturday. 1 day after? Good! Should received cashback later

)
Currency transacted / Posted : $1 -> MYR3.2675
Cash Back Earned : Not getting it yet, wait next month

Added on October 11, 2011, 4:16 pmedit date & time for easier to read
Added on October 11, 2011, 4:21 pmso from my own experience:
1. YAHOO US will follow US date & time
2. 2CO will post 1 day after
This post has been edited by erry-: Oct 12 2011, 02:24 PM