The Google+ Platform is still a relatively small collection of read-only APIs, but Google is definitely preparing for a wide and varied set of features for developers.

At the Inside Social Apps conference in San Francisco Thursday, Google+ engineering director David Glazer (pictured) revealed that Google will roll out more enhancements to the social networking platform “when we’re delighted with how it’s working.”

It’s a vague answer to an important question, and it has a lot of impact on whether or not developers choose to build on top of Google+, and thereby increase its user base and time on site per user.

But Google sees more value in a carefully planned-out debut for its social platform features than in a wide-open free-for-all.

“We made a very conscious choice to roll Platform out deliberately… when it’s ready,” said Glazer.

The company’s first priority has been creating a wonderful user experience on Google+. Secondarily, it has been weaving the Google+ features and experiences into Google’s own web products. Letting others integrate that experience via the Google+ Platform is a tertiary endeavor.

Why tertiary, many developers are asking. Why the delay?

“We wanted to avoid hurting our users and hurting our developers,” said Glazer.

“If we encourage to do thing while we’re still evolving policies and norms,” Glazer explained, “we get thousands of people building on the platform, then we have to announce more changes.”

His words are a subtly veiled jab at Twitter, which has struggled with developer relations over the past couple years. Twitter had gained something of a reputation for last-minute API changes and business-plan shifts that routinely pulled the rug out from under many a Twitter-based third-party application company.

Google is willing to take things slowly in order to avoid the same series of mistakes.

On a more forward-looking note, Glazer said he sees great things coming for Google+ third-party devs with Hangout APIs and mobile applications, in particular.

“The Hangouts API… there’s some really exciting things we’re seeing there. There’s going to be a lot of opportunities,” he said.

As for mobile, Glazer stated the obvious, saying, “Mobile in general is obviously growing at a faster rate… Google+ will see a lot of traction on mobile devices.”

Saying that mobile-specific Google+ APIs are “absolutely” coming down the pipeline, Glazer continued, “Anyone who builds an application on a mobile device has a set of features around location and communication. I want those APIs if I’m building on that device, and I also want APIs that show identity, sharing, and relationships.”

For all the coming Google+ Platform features, the Google team is considering implementations on desktops, on the mobile web, and on “the leading native platforms, “said Glazer. “We’re always aiming for those capabilities.”

In conclusion, Glazer summed up the point of the Google+ APIs:

“People care about other people, and that should be baked in as an option for what you do online… We can make everything you do online better if we have some idea of your identity and your relationships, and we think that can help almost every other experience on the web, too.”