The reviewer was most likely referring to mirrorless cameras with relatively large sensors, especially APS-C models and Micro Four Thirds cameras.

From the examples mentioned in the answers, APS-C mirrorless cameras such as the Sony NEX series and Samsung NX models fit this idea well: they offer DSLR-like sensor sizes without the DSLR mirror box, and they do use interchangeable lenses.

Micro Four Thirds cameras are another non-DSLR category with larger sensors than typical compacts. Their sensors are smaller than APS-C, but still much larger than those in most pocket cameras, so they can deliver better image quality than standard compacts.

There are also fixed-lens cameras with larger-than-usual sensors. One answer mentions the Sigma DP2, which uses an APS-C-sized sensor but has a fixed lens. Larger-sensor premium compacts were also cited as a compromise when interchangeable lenses or APS-C sensors were not available at the same price.

So the short answer is: the reviewer likely meant mirrorless interchangeable-lens cameras first, but possibly also a few fixed-lens large-sensor compacts.