Not that it’s exactly a race anymore; the game has clearly changed massively with satellite operators such as Planet Labs, the company also largely responsible for PSLV seizing first place in this category. Planet Labs placed 88 of its “Dove” CubeSats into orbit on a PSLV last February, and another 48 aboard Soyuz last Friday. These are imagery spacecraft, designed to completely rewrite the rules of satellite image procurement — instead of building massive, expensive, highly sophisticated spacecraft akin to spy satellites, they’re building CubeSat with relatively inexpensive cameras — but lots of them. Their resolution is less, but the availability is much greater, and although the satellites are so small and light that they don’t stay in orbit for more than a few years, this also means they’re self-cleaning and easily replenished because they are so cheap. It also partially compensates for their small size — they’re dwarfed by the big commercial imaging sats (to say nothing of spy satellites) but they fly much, much lower.
The primary payload aboard this flight was Kanopus-V-IK, a Russian civilian imaging satellite operated by Roscosmos for the purpose of emergency response. It carries multispectral imagers particularly useful for tracking wildfires. Kanopus-V-IK is a traditional spacecraft, large and equipped with propulsion. The Doves were not its only smallsat neighbors for the flight; other payloads included eight Lemurs from Spire Global (to provide weather forecasting information), three CICERO cubesates from GeoOptics (Spire’s closest competitor), two LandMapper-BC cubesats from Astro Digital, Tyvak’s experimental NanoACE (to test propulsion for nanosatellites; Tyvak is a launch broker), the Flying Laptop (a smallsat capable of searching for NEOs while testing a new type of On Board Computer) from the University of Stuttgart, Technosat from the Technical University of Berlin, Norsat 1 & 2 (Norway’s first scientific satellites, to improve merchant marine tracking and communications, and originally scheduled to fly on a Soyuz out of French Guiana), the Japanese WNISAT 1R small weather satellite, the crowd-funded Mayak solar sail from Moscow Polytechnic University (which could become brighter than the ISS when deployed), and four other Russian CubeSats.
FYI, third place is 37 satellites. It was set in 2014 by a Ukrainian-built Dnepr rocket out of Dombarovsky Air Base in Russia. The fact that the three records have all been set in the last five years — and with such a huge gap — is indicative of a major trend in spaceflight. Things are changing.