I design for Sekimori Design and I can guarantee you that Stacy will not be receiving a similar letter from Six Apart because Stacy worked out an agreement with Ben and Mena long ago. They are aware that our sites are Movable Type based, and we put the Movable Type logo on the sites as required as per the licensing agreement. However, we do not profit from Movable Type. We install the software, as long as it's on the same server we suggest hosting from, for free. (Installs are so quick on this server we can literally do them in our sleep.) If it is on a server we are unfamiliar with, we refer them onto Ben and Mena's pay-installation service. Several of our clients have chosen this option. Then when the software is safely on their sites (set up by Ben and Mena), we go in and "wrap" the design around it.
We are bound to request all of our clients purchase an MT licensing agreement. Although we cannot enforce this, we certainly -- highly -- suggest it.
We also are not allowed to provide any type of support for the software post-installation. Any support inquiries are referred to Ben and Mena immediately, as our hands are legally tied in any and all issues. (Not that we're complaining. That just makes our job that much easier.) And again, we highly suggest they purchase the licensing agreement if they haven't already.
We are also not allowed to advertise any affiliation with the Movable Type software whatsoever. We are not affiliated with them. It just happens to be our software of choice.
Sekimori has taken great pains to operate WITH Ben and Mena's knowledge, and within the boundaries of their licensing agreement.
I asked for permission (which they granted) to post this to set the record straight.