From a retail industry perspective, 2010 will go down as the year mobile went mainstream, the economy recovered from the crash, and Facebook surpassed Google as the most influential online property. While the economy certainly had the biggest impact on the retail industry, a few big companies also exerted influence. Here's a rundown and a look back at 2010:

Apple -- Steve Jobs and company continued to lead the mobile pack. Consumers are using their iPhones to shop, retailers are using the iPod Touch for mobile checkout, and both are embracing the iPad as the next wave of technology.
The Next Technology from Apple
Mobile Platforms in Retail
Apple Stores, Touch2Systems, and the iPad

Google -- Not to be outdone, Google's Android platform grew faster than Apple's, plus they support QRCodes natively and will probably beat Apple to NFC. Google Checkout, Product Search, and Boutiques.com continue to impact the e-commerce scene.
Google Leverages Like.com

Facebook -- While the movie The Social Network certainly made Facebook a household name, Connect, Places, and seeing the "like" button all over the Web really pushed Facebook everywhere. 2010 set the foundations for f-commerce.
Facebook Participatory Promotions
Crowd Savers
What's the value of a Facebook fan?
Step Aside Google
Leveraging Social Networks for Retail
Social Shopping at Nine West

Groupon -- This newcomer executed on a simple concept flawlessly, making them the fasted company to reach $1B in revenue. (See cool chart from Silicon Alley Insider.) Google's offer of $5-6B wasn't enough, so now they are raising an additional $1B in funding, presumably to buy-up all the copycats across the globe.
Changing the Way We Shop

Amazon -- As if leading the e-commerce charge wasn't enough, Amazon shook things up with their purchase of Woot and release of their Price Checker mobile app. They continue to push boundaries with Kindle, and don't seem worried about the iPad at all.
You Can't Win on Price
Amazon Looks at Your Social Graph

eBay -- Acquiring Skype didn't exactly work out, but eBay's purchase of PayPal and RedLaser are driving the company forward. They are still a major force.
Bump the Bill

Oracle, SAP, HP, IBM, and Cisco left their marks on the retail industry as well with various acquisitions and CxO shake-ups. We'll just have to wait and see what 2011 brings next.