Seniors have a significant presence on Facebook with women in this age category up more than 175% since fall 2008 and men up almost 138%, according to the Pew Research Center and eMarketer. Varsity, which focuses on senior marketing research, points to AARP.org's year-old social networking platform - which now has 350,000 users in 1,700 groups - as additional proof that seniors have become an important social network constituency.

Twitter, though, is an exception, Amy Beamer, COO, tells MarketingVOX. "We are not seeing that many tweets from seniors. Facebook, yes. Blogging, definitely yes." In some part, this is a reflection of larger trends: Facebook is growing faster than Twitter, generally.

But for seniors specifically, Facebook is more attractive from a utilitarian perspective. "It is easier to keep up with grandchildren or adult children on Facebook." There are ways Twitter marketers to reach out to seniors, however, Beamer says.

1. Give them a better sense of what is in it for them to use Twitter. Such strategies could be anything from offering coupons or Twitter-specific sales to enticing people from their generation to Tweet on issues.

2. Identify the topics in which they are interested. For example, there were signs that seniors were following the health insurance overhaul debate on Twitter, Beamer says. Less obvious but equally compelling topics would be RV travel or time share management - subjects of big interest to active seniors.