SiliconValleyWatcher reports that about 1800 Google marketing people from its offices around the world are at an internal sales conference at a secret location in San Francisco, being briefed on a completely revamped Google Adwords/Adsense program and other new features.

As well as being an important source of revenue for Google, the Adsense program has been successfully used by many bloggers to provide a regular (if not always large) source of advertising revenue.

The report speculates that the changes may include the ability of advertisers to be more selective as to where their ads appear, which could potentially limit bloggers income, as well as new tools to compete better the services such as those provided by Kanoodle, who’s advertising is already appearing on a number of well known blogs.