My colleague Pete Smith (who also writes for this blog) has a very nice piece on how to protect yourself in the event that your firm undergoes a merger. In a nutshell, he underscores the importance of keeping up with what is going on inside your law firm (i.e. beyond the practice of law.)
Information is power and burying yourself in your office may not be the best survival strategy in a world where a huge percentage of law firms are contemplating a merger. I agree with Pete that it is important to keep your ear to the ground and learn what you can about the inner workings and financial health of your firm and of your practice group. But law firm failure is also a fact of life so it is important to keep up your network beyond your firm. I have written about this here.