The next time I hear this term, I'm handing the speaker an enrollment form for the fifth grade.
There is no such thing as "Reverse" racism. Any irrelevant use of race to make a decision is racism.
For my non-American readers who are looking confused: America has a long ugly history with racism in which European descended people, ("white") thought much less of African descended people ("black"). So later on, it became apparent that some "black" people were equally contemptuous of "white" people. Although both reactions are racism, people have somehow filed away the term "racism" to mean only the first one. So when the second occurred, they saw it as being like the first one, only in reverse.
I most commonly hear this come up in discussions about Justice Sotomayor and her nomination to the Supreme Court. Her honor Soytomayor is Hispanic. Many in the right wing worry that she will be racist towards "white" people. Except that they don't phrase it that way.
I'd also like to remind people that racism is the unfair discrimination based on race. Unfair discrimination based on other things is not racism. Unfair treatment based on gender is sexism, unfair treatment based on age is ageism, and unfair treatment based on social class is classism. One cannot be "racist against old people" because being old is not an ethnic identification. (The old age example would be "ageism.")