Since Akismet's spam database is an aggregate of information created, and ongoingly contributed to, by the WordPress community, I see a problem with Akismet becoming a pay service. As Akismet works best when all WordPress sites use it, as sites quit using it Akismet will potentially become less valuable and reliable.

It is interesting to me that the new description of how Akismet works no longer mentions the reputation based nature of Akismet's spam ID functionality and the WP community input. I wish Matt and Automattic would rethink their effort to Akismet a pay service.