Two recent entries of note:

• ProgrammableWeb.com » Blog Archive » API News from Where 2.0 is a good pointer to some of the new developments in this space. This week has been is a busy week for developments in online mapping because of such events as the Where 2.0 conference, the Google developer Day, WhereCamp - alternative conferences for geohacker.... It seems that people who have stuff to show off want to wait until these big conferences to announce their advances.
• ProgrammableWeb.com » Blog Archive » 44 Mapping APIs gives a breakdown of the mapping related APIs. It's helpful to have a conceptual framework for approaching this fast-growing area of mapping APIs, especially if you want to look beyond the Google maps API.