Here.
For those of you fortunate enough to see Thomas' presentation at PASS last year on how the SQLCAT team set the ETL World Record then you will already know that this paper was in the works. However, for the vast majority who didn't get to go, Thomas mentioned as part of his presentation that the SQLCAT team were putting together a White Paper on Data Loading best practices and learnings from the field.
The great news I received from Thomas today is that this paper is now available on MSDN http://msdn.microsoft.com/en-us/library/dd425070.aspx. The actual announcement is on SQLCAT.com here.