For the first time, more smartphones where shipped than PCs. This important milestone helps reinforce that retailers need a strong mobile commerce strategy. IDC reported that for the 4th quarter of 2010, manufacturers shipped 100.9 million devices versus 92.1 million PCs shipped.

One early adopter for the retail industry is eBay, the popular online auction and shopping site. In July 2008 they released their first mobile app and have increased investments ever since. In 2002 they bought PayPal for use with its online channel, but its becoming a force in the mobile world as well. In June 2010 they acquired RedLaser, the popular barcode scanning mobile app. Both pieces of technology enhance the mobile experience, and are available to other retailers as well.

More recently, in December 2010 they acquired Critical Path Software, the developer of their eBay, StubHub, and Shopping.com mobile applications. Taking their mobile development in-house was a clear signal that mobile commerce is important to their strategy.

Pop on over the eBay Inc's mobile commerce stats page to see just how well they are doing. You can use the animated map to see where people are using the app on any given day, and you can compare sales of the different categories.

eBay's hottest category is Cars & Trucks, garnering 16.5% of the total $2B (yes, billion) in mobile sales in 2010. To understand why that category is so large, let's look at the top 10 most expensive cars sold on eBay mobile in 2010:

$240,001 Mercedes-Benz: SLR McLaren
$209,888 Lamborghini: Gallardo
$208,500 Ferrari: 430
$199,900 Lamborghini: Gallardo
$189,000 Lamborghini: Murcielago
$185,000 Ferrari: 430
$175,000 Porsche: 911
$170,000 Ferrari: 550
$160,000 Bentley: Continental, GT
$159,900 Lamborghini: Gallardo

eBay claims they sell 3-4 Ferraris on their mobile app each month. Yes, mobile commerce is not limited to small items. While I would wait to get home and fire up the PC, the current generation that has grown up with mobile phones has no issue satisfying their impulses. Dave Sikora of Digby told me he's seen people buy furniture sets, mattresses, and diamonds via their mobile phones.

I guess mobile commerce is rapidly becoming the norm.