Personalization: implicit vs explicit (2)

Personalized News: A Market Overview is a good review.  As Greg, founder of Findory, indicated, implicit way of personalization is still working in progress.  The best approach will be a combination of implicit and explicit. 

On the explicit side, users need to get good ROI: return of investment.  Users spend certain amount of time to specify their own preference. They need to be convinced this investment is really worth it.