I second and third this. When I forward messages to Gmail, it tests the previous address's IP against the SPF record which returns a FAIL on every forwarded email.
For instance, if an email from firstname.lastname@example.org is sent to email@example.com then firstname.lastname@example.org forwards to email@example.com. However with no rewriting or enveloping of the headers to indicate that it was forwarded Google will match the sending IP of dreamhost.com agains the SPF record at mydomain.com which will always be incorrect. It should be matching the sending IP of dreamhost.com against the SPF record of dreamhost.com as it does with emails forwarded from my work email server and domain.
Please fix this.