Sort of, but not exactly. It's not API compatible with Chef server, and I believe you don't get the nice search syntax for grabbing node information across your fleet that match some kind of criteria. But you still do get info on your other machines, and you do get nice orchestration across your fleet.
you get a much better orchestration as you could with chef server
you also have much faster interactions, better life cycles
and to the searching... you get every information of evert machine under your fleet
it is much much more better the chef server
OpsWorks gives you better features, try out to start a small stack and then also have a look at the default cookbooks, there you can see what you can do with OpsWorks: https://github.com/aws/opsworks-cookbooks
I have a webapp that I built, that utilizes rackspace's API and chef. I have a chef server that I use for all my configuration management, I have a Rails app that I use to talk to my chef server to manipulate machines, or rackspace's api to spin up machines, and I am building "triggering" into it (low disk space, high CPU do X). I am able to change IP addresses, spin up a machine with a specific stack etc. Granted this isnt the default chef-server, but the ability to do all this stuff, and not be locked into AWS is there.