As the e-commerce vs. brick-and-mortar war continues, here are some headlines from the front lines of the conflict:

Nielsen Launches New E-commerce Measurement System

The ratings company Nielsen is launching a new measurement service for e-commerce sales, tapping data from over a dozen large retailers, including Target, Peapod and Giant Eagle. While companies like Slice Intelligence and InfoScout give e-commerce estimates based on panels of consumer receipts, Nielsen thinks using actual sales data will provide a better picture of the e-commerce market. [RetailDive]

Thrive co-founders Gunnar Lovelace and Nick Green have raised $58M for their startup over the past 15 months, after being rejected by over 20 venture capital firms when they originally went in pursuit of cash. The startup, an online organic-food and natural-products marketplace, uses a membership fee of $60 per year to slash prices 25% to 50%. Now that they're successful, investors from Greycroft Partners to Demi Moore all want a piece of the action. [BI]

Online Marketplace Gets 90% of Sales Through Instagram-like App

As people purge their homes to resell goods online, one online marketplace, Poshmark, gets 90% of those sales through its app interface. The app rewards buyers and sellers through a “social selling model” where users are encouraged to find, connect and share items they like on their profiles—bringing social networks to eBay. [RetailDive]