I have had a quick read through of the, just published, Portal 6.1 tuning guide.
Generally I would describe it as a "mostly friendly" read.
I was pleased to see a section on "Recommended database maintenance for DB2". This is something that has been on my mind for a while - especially for SMB installations where true DB skills would be a "nice to have" resource. There is also a section on DB2 database tuning showing how the teams test setup was altered.
If you are interested in Portal 6.1 from a technical aspect - you really should read this.
Portal 6.1 Tuning Guide