Schmidt joined the Apple board August 29th 2006: http://www.apple.com/pr/library/2006/08/29Google-CEO-Dr-Eric...
Public iPhone announcement was January 9th 2007: http://www.apple.com/pr/library/2007/01/09Apple-Reinvents-th...
Also, the book that article is sourced from hashes out how the Google mobile software team working on iOS which was lead by Gundotra was a different body all together from Rubin's Android unit (who were actually gunning for Android to be shut down since they couldn't see the point of it). It's worth a read.
* I don't think you can minimize the boost android got by having eric on apple's board during a very critical formative point
* Google completely abandoned their earlier prototypes once they saw (in the apple keynote) what apple had brewing.
If being on the board was so helpful, then why would Google need to abandon their previous approach?