What is Long Tail first of all? You can find the definition of Long Tail in my personal blog. How can long tail play within marketing? It really tells us that we must think both big and small when marketing and in a business. Although the popular products/services makes up the most sales (the head); the less popular ones (the tail) when added up together can rival or even outperform the most popular ones. Of course, this can really only happen outside of traditional brick and mortar business models. However, there are still marketing implications of long tail:

For long tail effects to work in marketing; you need to target both the head and also the tail.
1.) Marketing not just targetting the popular media but also targetting all other smaller niche ones. Chris Anderson has summarised a PR week article in his blog on how long tail can play in Public Relations (PR), which gives a very good explanation of how we can look at long tail in all other areas of marketing:
An article on how PR professionals can play the Long Tail: “In the ‘Long Tail,’ media coverage comes in great and small numbers, and they all have influence,” Steve Rubel says. “Putting bloggers on the same playing field [as the national press] – that’s ‘Long Tail’ thinking.” Dan Berkowitz says that most PR professionals target the major business press, but that strategy is more complicated now due to media fragmentation. He suggests going beyond “the media” and targeting all manners of influencers. Berkowitz notes that some PR professionals might balk and say, “This is just overwhelming. I can’t think of these 300,000 little outlets.” But he adds that applying “Long Tail” thinking to PR is merely a new challenge that requires them to be more open-minded.”
2.) We need to look beyond traditional offline marketing mediums such as TV; radio; newspapers; and look into the both online as well as other new marketing mediums.
3.) In search marketing; we need to target both the most popular and least popular ‘relevant’ keywords
– Top 50% of queries = 80% of volume
– 80/20 rule does not regularly apply to search
– Focusing on just the first 20% of keywords will invariably miss most of the value