You can pick a few meetups (or even just one) to focus on, or you can be on the lookout when you meet casual acquaintances (perhaps at other social events).
I wouldn't want to spend all my social time in work hunting mode, but a small regular investment can pay dividends (depending on how happy you are in your current position).
Another reason to do such activities is the opportunity to help others. I love when I am talking to others and find out about a position that isn't a fit for me, but may be great for someone else I know. Hooking up two acquaintances in a possibly mutual beneficial way is low energy (not too much work) and yet high impact (people remember who helped them get a job).
I discovered this can be as easy as clicking"like" on a LinkedIn in post: http://www.mooreds.com/wordpress/archives/2180