AdAge reported on last week’s Google press event, where  vice president of product management Neal Mohan explained how the company plans to extend its advertising empire beyond search keywords.

Google will be trying ways to serve more display ads — that’s industry jargon for Internet ads not targeted to search results — throughout its popular properties.

But Google spokesperson Rob Shilkin explained to VentureBeat that “display ad” doesn’t necessarily mean gaudy, dancing images.

“The Google Display Network already exists,” Shilkin said. In an email, he wrote, “Google Display Network = YouTube + Google sites + AdSense/Ad Exchange partner sites.”

AdAge reporter Edmund Lee concluded that “a substantial part of Google’s display success hinges on its ability to milk YouTube, Gmail and Google Finance.” Already, Google Finance sometimes runs rectangular animated display ads alongside stock information. But Shilkin was clear that this doesn’t mean Gmail is about to start hosting similar image, animation or video ads. “A display ad can also be text,” he said.

One of Gmail’s seductive traits has been that ads in the system are displayed to the side of the screen and are text only. Compared to Hotmail and other services that stuff ads, sometimes consisting of big images, into the middle of email messages, Gmail’s ads are barely intrusive. Shilkin said the company has no plans to change the successful format.

Mohan said last week that today’s display market is about $20 billion per year. “We think it can be … $40 billion, $60 billion, or $80 billion,” he said. There are some big hurdles to be leapt first. For starters, complicated processes for buying display ad space can stall the launch of a campaign for a month or more. Compared to Google’s nearly instant do-it-yourself targeting system for search keywords, there’s obviously room for a major overhaul of how display space is bought and scheduled.