If you do have a powerful gaming laptop that does not yet have a built-in stereoscopic 3D display, they you might be able to connect an external 3D-capable LCD monitor to it and still play games in stereo 3D mode. In order to be able to do that your laptop will need to have a Dual-Link DVI video output and unfortunately not a lot of the newer gaming laptops do feature DVI connectors for external monitors. HDMI can be an option too, if you get some of the upcoming HDMI 1.4a stereo 3D-capable solutions, but you will be limited to the restrictions of 720p 50/60Hz 3D mode and the 1080p 24Hz 3D mode. But you may get another chance if your laptop also has a DisplayPort connector, however you will also need an active DisplayPort to Dual-Link DVI adapter.
However you should be careful when choosing a DisplayPort to DVI adapter, as there are different solutions that offer different capabilities. There are basically two types, a cheaper passive adapter that only supports Single Link DVI conversion that is not Ok for a Full HD 3D-capable monitor, the ones that you should look for is an active adapter that converts DisplayPort to Dual-Link DVI. The active DP to DL DVI adapters do need more power and thus they do have an additional USB connector that is needed also to be connected, but this also makes the adapter much more expensive than the passive Single-Link models. With all that said, getting a DisplayPort to Dual-Link DVI adapter does not guarantee you that everything will work as expected, although in theory it should be enough for you to be able to connect and use a 3D-capable monitor. So if you have already used one such adapter and can confirm if it works or not for connecting a 3D-capable display to your laptop. Currently there are no officially certified adapters that will guarantee that everything should work as expected when connecting a 3D monitor, but apparently Nvidia is considering to offer such adapters if there is interest in them. They have setup a poll in the official 3D Vision forum asking if users are interested in such adapters.