The Twitter ecosystem may be changing constantly, but most of that comes on the back of individual developers and outside companies. They beat on Twitter APIs to create new products that may win them glory, recognition or cash. Over the past month, though, Twitter itself has gotten into the game, releasing or announcing a handful of new features.

A new function for "retweeting" (echoing another's tweet to your own followers), changes to how trending topics are managed, and the ability to create lists are new tools intended to engage users ... on the Twitter.com website. Considered within the context of Twitter's changed terms of service this year, the upgrades may be part of a broader ad-based revenue plan.

Modest goals don't seem to be on the agenda for Facebook. Sheryl Sandberg, the company's chief operating officer, is shooting for Google (NASDAQ: GOOG). The social networking company seeks its ad market as rivaling (or even surpassing) Google's search ad market in size. Facebook says it's on target to bring in $500 million in revenue this year (Sandberg didn't confirm it, though).

With its 300 million users, Sandberg has been trying to convince the world that her company has a solid business model in place. The perception that eyeballs don't necessarily equal dollars, born of the internet boom a decade ago, isn't necessarily true any more, as demonstrated by Google's ability to monetize search (and hit record profits) has demonstrated. For the third quarter of 2009, the search engine giant raked in net revenue of $4.38 billion.

Baidu Inc. (NASDAQ: BIDU) CEO Robin Li has high hopes for Phoenix Nest, his company's new advertising system. While many investors worried that Phoenix Nest, launched in April, would negatively impact revenue, Li thinks that the system will actually boost sales over the longer term.

In an interview with Dow Jones, Li confessed that revenue has suffered modestly since the launch of Phoenix Nest, primarily due to the fact that Baidu has been offering advertisers incentives to switch to the new system. However, he added, "Going forward, Phoenix Nest will have meaningful positive impact to our revenue."

Tomorrow morning before the bell, The Washington Post Company (NYSE: WPO) will have its chance to impress Wall Street when it reports its fourth quarter numbers.

Going into tomorrow's announcement, analysts are expecting the company to show earnings on the quarter of $8.17 per share. Should the company hit this estimate, it would be a decline of 16.5% from its reported $9.79 during its fourth quarter 2007.

Among the companies reporting earnings on Friday were Gannett Inc. (NYSE: GCI), the largest newspaper publisher in the United States, and Chevron Corp. (NYSE: CVX) the second-largest U.S. oil company.

Gannett reported fourth-quarter earnings down 31% on falling revenue from newspaper and broadcast ad sales. Earnings fell to $245.3 million, or $1.06 per share, for the three months ending December 31, from $353.5 million, or $1.51 per share, in the year-ago period. Excluding a one-time charge, profit was $1.28 per share. Analysts surveyed by Thomson Financial had expected net income of $1.27 per share. Quarterly revenue fell 12% to $1.9 billion from $2.2 billion in the 2006 fourth quarter. Analysts forecast sales of $1.98 billion.

For all of 2007, Gannett earned $1.06 billion, or $4.52 per share, down from $1.16 billion, or $4.90 a share, in 2006. Analysts had expected $4.42 per share. Revenue fell to $7.4 billion from $7.85 billion in 2006.

Gannett shares rose 1.46% on Friday, closing at $37.47. That's up from 52-week low of $31.97 in early January.