If it is proven that the Syrian government used chemical weapons in this case, then I believe we should take action. Not necessarily action to remove the government from power, but tactical strikes on stores of chemical weapons and any facilities used to direct their deployment.
I hear a lot of people saying "it's not our war" and such like, but I disagree. Irrespective of the difficulties such situations pose (and they are many, whichever action you take), ultimately we are facing a humanitarian crisis that we may have the technology to stop. Where innocent children are being slaughtered in the most excruciating and heinous fashion, I believe it is the responsibility of everyone with a moral compass to do whatever they can to make it stop. It's not the same as Iraq or any of our other recent mistakes; this is about saving lives that are being lost, not speculation on potential threats or a venture to acquire oil. If ever there was a purpose for having the UN, this is it.