Of course there is such a thing as a real random number generator. It's just not very feasable to use for a large poker site. There are many implementations, either you can use a radioactive substance and measure the time between discharges (completely unpreditable), or you can a CCD chip held in complete darkness (see
http://www.lavarnd.org/ ).
Of course, it's been shown that a pseudorandom number generator that is seeded by a true random number is, for all practical purposes, just as good as a real random number generator.