By Tammy Casserly

As smart companies such as Procter & Gamble, Bank of America, Apple, Microsoft and Google move ad dollars to where the consumers are, it's clear that mobile marketing has hit a tipping point.

P&G, the leading consumer packaged goods giant, has said it will spend "a lot more on mobile advertising" as a percentage of its total estimated $6.7 billion budget this year.

P&G is just one of the consumer brand titans to realize that an estimated 255 million mobile phone users nationwide -- all with built-in demographic analytics tracking that can shout out personal buying behavior instantly -- are choosing the mobile channel.

Marketers who have yet to develop a mobile marketing strategy need to take a close look at how mobile will affect their planning this year and beyond.

The trends and challenges outlined below brush the surface, but can help outline opportunities so that marketers can start planning their mobile strategy now.

â?¢ Brand image campaigns. While 2007 was all about text-based campaigns, new handsets and networks will support image-based campaigns using video, MMS, mobile Web and even television.

â?¢ Integration is key. To maximize the opportunity to create a dialogue between the brand and consumers, plan today to integrate mobile tactics into the more traditional channels of print, radio, TV and online. A mobile call to action will be the key to success.

â?¢ Local rules. Mobile search and voice-based marketing campaigns targeting local niche audiences are in use by early adopters in industries such as travel, entertainment, quick-service restaurants and consumer packaged goods -- as well as marketers who see the value of being in front of the consumer in more local contexts.

â?¢ Get mobile search ready. Adapting your site content now for mobile access takes only a few simple steps. Tackle this effort now to ensure you can be found without investing a single dollar to promote yourself or your client to an exponentially growing audience.

â?¢ Mobile music, ringtones and gaming will thrive on ad sponsorship. With prices going down (99 cents from Sprint for a full download) the mobile music, ringtones and gaming economy will boom with ad support -- like the present day radio and Internet -- providing more mobile assets for the total ad spend.

Mobile devices have become lifestyle products, not unlike the grandfather of all mobile devices, the car.

Marketers who devise programs that address the consumer on the go will grab the most visibility on a person's mobile phone and will reap rewards in market share.

Tammy Casserly is president of Wilde Agency, a full-service marketing agency in Holliston, MA. Reach her at .