Don Shelkey, the author of Enforceability of EULA’s  is a lawyer (not providing legal advice, of course). This article provides a quick review of how the courts have viewed End User License Agreements. It appears that in many cases, a click-through license agreement is enforceable as a contract. Good to know if you’re either clicking through, or creating/choosing a EULA for your software.
This still leaves the GPL untested. Given that there’s no “consideration” for GPLed software, and that you generally don’t even clickthrough and many GPLed packages, the GPL will probably still have its day in court.
 [link goes to MirrorDot because the original seems to have gone off the air]