Jay Jamison writes:

There are two broad categories of interest-based networks, and both are seeing companies succeed in 2012. One category is verticalized, subject-themed networks such as Foodspotting (food), Rapgenius (rap lyrics), 9Gag (humor), Wedding Party (weddings) and Fitocracy (fitness). The promise of these services is that they deliver value to users in a specific slice of their lives. They create strong, loyal communities that can be valuable targets for brands. The challenge they face in the evolving ecosystem is how to sustain growth and user acquisition given their vertical focus.

The other approach is horizontal: Pinterest, Quora, Path, Thumb and PandaWhale. These services span a broad range of topics, but offer a different interaction model — whether through pinboards in the case of Pinterest, or questions and answers in the cases of Quora and Thumb. These networks have broader audiences that can be spliced into specific targets, but will require large scale to deliver meaningful targets in specific areas (e.g. number of users on Quora that are interested in a particular topic). In this segment, the mechanics for driving engagement and analytics will be very important to delivering advertising targeting and conversion.

First off, thank you for mentioning PandaWhale!

It's flattering to be listed in the same breath as Pinterest, Quora, Path, and Thumb, since we're just getting started and they already have tens of millions of users.

Second, thank you for showcasing our interest in Interest Graph.

Every time a PandaWhale user creates a stash or follows a stash, that person is demonstrating interest. Little by little, the interest graph will come to reflect what we're actually interested in.

We have a long way to go. But I'm excited about evolving PandaWhale in 2013 as we grow from hundreds of thousands of monthly active users to millions.

Meanwhile I am stashing Jay Jamison's Interest Graph article.

super article.  awesome that pandawhale was in that mix.  well-deserved, adam!  and, hey, jay jamison... i officially take back the banker comment.  any investor that recognizes that mashup is the new vertical is an investor with vision in my book ;O)

Jay also points out why Brands are interested in Interest Graph:

The fact that the relationship between social and mobile networks and brands is still maturing bodes well for start-ups, as they are nimble enough to test the countless avenues toward revenue. This is especially true for the interest-based social apps and services, which are known to quickly gain users and engagement. Brands are going to be looking for scale and how much time their users spend on the service interacting. By focusing on building a great community, there will be an opportunity to ride the wave of advertising dollars that will inevitably shift into social and mobile as brands adapt. Start-ups also need to think about what an ad unit really means on their service and how they can monetize their brands without compromising their product experience. The aperture for advertising is more important than ever in mobile and it is something that both brands and start-ups need to work together on to get right.

There are no best practices for brands advertising on mobile yet.

This includes not just mobile apps but the mobile Web.

Speaking of which, there are no truly great mobile Web sites yet.