Via Motionographer is Steven Heller’s Olympic Icons: an Animated Appraisal at The New York Times website:
See also The Graphic Design Olympics (2004) by Interesting recent work includes pictograms developed for the 2008 Summer Olympics in China by a former Adobe guy; see The Graphic Language of Min Wang.
Symbol Sourcebook), Otl Aicher, Otto Neurath, Paul Rand, Edward Tufte, and others.
A few sentences on the subject can only be inadequate. For more info, see Navigating Today’s Signs: An Interview with Mies Hora by Steven Heller and Critical Wayfinding by Ellen Lupton and J. Abbott Miller. "Modern Hieroglyphs" in Design, Writing, & Research by Lupton and Miller (excerpt pdf) makes a really cool use of pictograms in explaining pictograms in design and history.
Update: Slate has 6-part series on The Secret Language of Signs, which includes why signs are better now than they've ever been, why the signs in Penn Station are so confusing, how smarter signs could make London easier to navigate, and the international war over the exit sign.
See also How and When to Use Pictograms from Pixel Resort.