It depends. When in doubt, the most important thing to ask yourself is, “What are my clients using?” More and more of us are signing up for Facebook accounts every year, including users over 65. On the other hand, the only people I know using Snapchat (the photo sharing app) have an average age of 14. Vine (the 6-second video app) is being leveraged by businesses of all types and some consumers. Pinterest (the image sharing website) is huge among women age 35-44.
If any of those are your target audience, you might want to at least read the Wikipedia entry to find out more, in case it comes up in conversation. You don’t need to use every tool, but being up to date is a quality we all look for in an attorney, and that includes knowing a bit about what’s happening online. Spend a few minutes on Google and you could learn enough to weed out new tools you do, and don’t, need to know more about.