Department stores, flash-sale sites and third-party retailers are leading the pack in terms of luxury retailers in mobile marketing, according to the L2 Think Tank Digital IQ Index.

Since a large number of luxury brands are steadily moving into the mobile arena, it is obvious that the smartphone reign of power has shifted over the past few years, and BlackBerry is decidedly absent.

A couple of months ago I was developing a mobile site for the No. 4 retailer, trying to create a way for users to pick many objects and extra functionality without forcing a page load.

Brands such as BMW, Lancome, American Express and L’Oreal have incorporated iAd banner advertisements into their mobile strategy, but this could mean that they are missing consumers without Apple mobile devices.

Approximately 61 percent of the 22 million wealthiest individuals in the United States own a smartphone, indicating a potentially untapped market for about 8 million smartphones, or 39 percent of the affluent, according to a recent study by American Affluence Research Center.

Luxury brands are developing mobile applications because they are already aware that a complete marketing strategy requires mobile marketing, but practically the entire industry is having trouble grasping the fact that they need to reach more than just iPhone users.

Gilt Groupe has gone cross-platform with the launch of a BlackBerry-optimized mobile site.

A study from Gartner predicts that revenue from application stores worldwide will surpass $15 billion in 2011 with an estimated 17.7 billion downloads.

What are the key trends with mobile applications and what will Apple, Google, Microsoft, Research In Motion and others do that will affect brands in their marketing and commerce?

Iconic jewelry brand Tiffany & Co. used mobile to promote its new product line to female consumers in their 30s who use iPhone or BlackBerry smartphones.