Summarizing the main points I've picked out of these comments. Anything I'm missing?

A) Github does not cover a lot work that is done because developers are prohibited by NDAs (for their day job) and/or don't have time/inclination to contribute to open source; furthermore OSS is less hot outside of silicon valley

B)Github is an important piece of an overall portfolio; for most employers it is not stand-alone in screening a candidate

C) A code portfolio (github or otherwise) is a complement to the information found in a resume

D) Resume should be used to highlight the most significant code contributions (in github or otherwise)

E)Control is important - developers should be able to hide some projects in order to control the image they want to project; it is important to position oneself for the specific jobs one is targeting

F)For hiring, you need a summary (that's easily printable) of everything that you bring to the table

G) For employers, interviewing is a huge time-sink; there's huge value in only bringing the most relevant people into an interview

Very solid article about blogging. It's timely, as I'm thinking about starting a business blog! In the summer of 2011, I blogged for fun about home cooking: www.foodisloving.com.

Two things I would add to the article:

1) The decision to blog or not to blog should be rooted in how you plan to reach your target audience and prioritizing your expected returns. Since you only have so much time in the day though, you may find that it's more effective to market to your target audience using other means. If SEO and referrals links are important to you, then blogging is absolutely a great way to authentically build your status.

Mark's target audience are tech entrepreneurs who hungrily look for advice online about how to build their companies. Hence blogging is an ideal means for him to connect with his audience.

2) In deciding who at your company should blog, make sure that the designated blogger is efficient at writing understandable and eloquent prose. Table stakes are that the blog must be easy and (somewhat) fun to read. Then you layer in Mark's point about saying something of use to your target audience

In addition to the bigger click target, I appreciate that more information can be included in the still-visible section of each sheet. Each page in a breadcrumb trail is limited to a word or two of context, but with sheets, there's room for titles and other useful info.

This article boils down to three main points:

1) Companies are better understanding customer psychology, especially when it comes to making purchases. Both understanding habit formation and probing receptiveness to marketing messaging are included in this bucket.

2) Companies are better able to draw correlations between pieces of known data. It's always easy to say at a 30,000 ft level that when it rains, more umbrellas will be sold; now those correlations are at the individual customers level.

3) Companies are betting linking together the understanding of customer psychology and the correlations of various customer actions, to improve their marketing. They can look for actions that cue them into what behavior status a potential customer is currently experiencing, and market with a highly targeted message.

All three of these points are ones that web companies have been working on many many years. There are certainly many more insights to unlock there, but what's particularly at the fore-front of data mining is the application of these three points to brick & mortar retailers, where data has traditionally been harder to collect and understand.

Yes, focusing on growth to firmly establish their brand as the go-to phone-to-phone sharing app. Network effects will help them keep that position once they attain it.

Also focusing on user engagement, as they are narrowing down on solving needs that are a) painful and b) frequent. They want users they've already attracted to be firing up the app daily, not weekly or monthly.