To the people ridiculing the OP, I think it's not an unreasonable question.
Such things do exist already, even on lower end machines, though they are rare. There are also USB display solutions.
My Toshiba U400 effectively has 3 video outputs, - HDMI and VGA on the machine and DVID on the dock. It's a 13" laptop and cost £550, so portability has little to do with it. I haven't been able to test the VGA and the HDMI simultaneously, so I don't know if it can do three at once but it can definitely do 2. Given that it can definitely separately drive the internal screen and the HDMI, and it can mirror the internal screen over VGA, I don't see why it wouldn't do two monitors, but that doesn't mean it will! The HDMI definitely does 1920x1200 and the graphics chip is capable of sufficient bandwidth to do 2560x1600 but I haven't found any documentation to indicate the machine's maximum external resolution, so I'm guessing 1920x1200.
The dock is a Toshiba Dynadock USB thing I picked up for £35ish on ebay and may be of some use to the OP. It is a universal dock and it uses a displaylink chip, which has Mac drivers - I tried it with a Rev B Air, but the resolution on the dock-attached monitor is limited to 1680x1050, though higher res is on the way according to a friend who works for Displaylink. They have mac drivers, but they're not a priority internally, so I suspect you might have to wait a bit longer on mac for something above 1680x1050. Displaylink products in general can be used in multiples, so you can already have multiple monitors on any computer with a free USB port, depending on your requirements for performance as USB isn't superb for full resolution video. It's fine for office and graphics work though, and full res video can use the HDMI instead. You can buy USB monitors from Acer I believe, that basically have one of these displaylink chips in them.
I wouldn't hold my breath for Apple doing this, and if they did it would probably only be on the 17". Partly this is just because I don't think they will think (possibly quite correctly) there is much market, and they'd rather we all bought a Mac Pro to go with the laptop. Also, given that Apple can drive 2560x1600 resolution, two of these would be a lot tougher on the graphics card requirements. This is already a bit of a bodge that requires a USB port to supply power to the adaptor unless you're using a 24" Cinema Display