"We all know of people who have jumped ship and found great success in a new company. Less visible are those who fail or flame out when they make the change. Although the figures are elusive, the majority of data I've seen suggests that 40 to 50 percent of new hires at the middle level of management and above have not succeeded in their new companies 24 months after hire. That means you have about a one out of two chance that things will work out when you join a new company in a managerial position."
The article reviews the various reasons to leave your current company as well as those to stay. There is no magical answer and only you know where you stand and what "may be" holding you back from advancing your career.
A caution I'll toss out is to determine how much of your dream job already exist in the current company. If you have not considered it, but you know your dream job likely exist where you are, consider how to evolve your career into your dream job.
Second, look at how many times you've discussed with various managers, (not just your own boss), what moves may be possible inside the company. If it is less than a few times, you may want to have some conversations with managers you trust and ask them what they see.
If some of these moves/jobs interest you, the next step is to determine what is holding you back. Current skills and capabilities or perhaps the company is no longer growing due to the economy. (Which may be worst in the next company you join, watch this carefully.)
NOTE: With all of this said, there is nothing wrong with talking to other companies about oppertunities they may have. Just always make sure to double check inside your own company before jumping ship. The pasture is not always greener on the other side of the fence...