Native advertising is big business these days. It represents a welcome good-news story for an advertising industry reeling from the twin assaults of ad-blocking software and growing public immunity to traditional ads. The days when a transitioning banner ad was enough to secure plentiful click-throughs appear to be over. Online promotions that resemble normal user-generated content (despite being paid for by advertisers) might represent an insidious blurring of formerly distinct boundaries, but they’re going to be a key marketing trend…