It seems now that almost every company is tied into Earth Day in some way, whether through sales on greener products, releasing or rehashing their environmental news, or throwing or participating in events like tree-plantings and park clean-ups.

Last year we took a look at the many ways companies participate in Earth Day, but this year we spoke with companies about how their interaction with Earth Day has changed, the relevance of Earth Day, and what value they derive from the day.

Timberland and Seventh Generation have in a way gone against the grain by placing less importance on the day itself.

"Twelve years ago," said Timberland CEO Jeff Swartz, "when Timberland first started organizing community service projects on Earth Day, it was a fairly episodic event: Take a day, shut down the office, everyone pull on their boots and go do something good for the environment. Twelve years later, the emphasis is no longer on Earth Day -- or any individual day, for that matter. Environmental awareness isn't episodic, it's ... something we apply time and effort against every day, in an effort to reduce our environmental impact on a much greater level."

Many other companies have changed what they actually do on or around Earth Day and where they focus their efforts.

Hewlett-Packard's view on Earth Day has shifted along with changes to its environmental programs, said Michelle Price, manager of worldwide environmental strategic marketing for HP's imaging and printing group.

Prior to the 1990s, the company mainly focused on itself and how to improve its own environmental performance. In the late '80s it started to move towards helping customers improve their performance as well.

HP measures it progress on a number of environmental issues, and shares its findings internally and with customers. "Through that, we use Earth Day as an annual reminder to evaluate our programs and challenge ourself to take things further," Price said.

It also used Earth Day to improve its internal communications when, in the early 1990s, it added a four-page pamphlet about its environmental efforts to its monthly employee magazine. From using Earth Day as a kicking off point for expanding employee knowledge of HP's efforts, the company now communicates with its workforce through regular updates via its intranet, email, Facebook, Twitter and team meetings.

Last year, communications company Alcatel-Lucent launched its Let's Be Eco-Friendly campaign, which was aimed at its workforce and raising awareness about the changes they could make in their daily work to use less energy, minimize waste and more.

This year, the company has organized Earth Day events at corporate and local locations. One change in its Earth Day communications is more emphasis on how it can help its customers reduce their environmental impacts.

FedEx was primarily concerned with environmental compliance throughout the 1970s and '80s, said Mitch Jackson, the company's VP of environmental affairs and sustainability. "Now, 40 years later from that first Earth Day, we focus on integrating environmental sustainability into business objectives, making it part-and-parcel of our business."