While many have been closely following the news of new social network projects from Google — whether it’s Google Wave, Google Buzz, or a rumored project reportedly called Google Me — the search giant has been rolling out a number of products that add a “social layer” to its search, sometimes quietly and other times with official announcements. Most recently, it announced Google +1, an application that acted as the equivalent of the Facebook “Like” for search results.

But perhaps the most apposite example of social web integration is the kind slowly being added to Google News. This is the search vertical that people often turn to for aggregation and current news (in fact, unless otherwise specified, most searches turn up articles less than a month old), so it’s not difficult to understand why Google would want to use it to tap into the immediacy of social media. Other algorithm-based aggregation sites have already developed similar measures. For instance, Techmeme announced earlier this year that it would begin publishing tweets as headlines. “It seemed as if something was missing in passing over tweets,” wrote Techmeme’s Gabe Rivera. “We’d miss the first few minutes of certain developing stories as well as opportunities for including good commentary. We also missed the chance to let certain sources simply speak under their own byline.” Google’s Matt Cutts suggested recently that publishers should tweet links to their articles immediately in order to get them indexed more quickly within the search engine.

I spoke with Jeannie Hornung, a spokesperson for Google News, about the various ways Twitter and other social media platforms are used by the aggregator. She pointed first to the “Most Shared” section, found on the right sidebar near the bottom of the main page. At the time of this writing, it displays headlines from a mixture of blogs and more traditional news outlets and allows you to sort the most popular stories by day, week, and month. (Only news outlets that are among the 50,000+ aggregated by Google News are included.)

But “most shared” in what way? While Hornung confirmed that Twitter was one of the signals used in this section, she said she couldn’t comment on the others. But the feature includes a drop-down menu allowing one to share these stories on various platforms — email, Google Reader, Twitter, Facebook, and Google Buzz — and so it wouldn’t be too presumptuous to assume that many of these platforms are used in the algorithm, as well.

Hornung also pointed out a feature launched just last week on Google News; if you click on a news cluster of stories from the front page, it now aggregates related tweets on the sidebar of that cluster. “It’s using the same technology that real-time search uses,” she told me, confirming that the tweets aren’t a raw feed, but rather are ranked by authority or “relevance.” Unlike the “Most Shared” section, however, these tweets do not all have links to stories indexed by Google News; they’re based, instead, on related keywords.

“The Tweets section appears when there’s a high level of activity on Twitter focused on that story and those tweets add diversity to the full coverage page,” Hornung wrote in a follow-up email. “For example, we demote tweets that are on a broad topic not necessarily tied to the specific news story, that simply restate a headline and/or that link to a story already included on the full coverage page.”

But I couldn’t help but notice that most of the social integration is only apparent on the sidebar, rather than within the main search results. Is it possible that the algorithm uses any incoming signals from Twitter to determine a news story’s prominence? As with most questions about the 100+ signals in Google’s algorithm, I got a “no comment.”

Hornung did say that the raw immediacy of social media is better suited for Google’s Realtime Search than Google News. “Google News is quite fast because it isn’t hand-curated,” she said. “Because it is an algorithm, it can see stories quickly, but it can only see them as quickly as publishers publish them so it can index those stories.”

While the idea of social media integration being added to all of Google News’ aggregation is appealing to a tech media reporter like myself, Hornung was more realistic in addressing Google’s approach. “I understand why you’re driving at that because it’s the premise of the story,” she said. “It really is — not to diminish it at all — it is an incremental enhancement to the full coverage page, not the main page. So I wouldn’t say adding tweets to full coverage is a sign of anything larger than a moderate enhancement to the full coverage page.”

Or, to put it another way: “It’s a tasty side dish.”