OCZ has introduced a new line of high-performance memory, coupling very fast ram with a new type of heatsink design to keep the units cool. The "ReaperX" series, as it is called, have two copper heatpipes attached to opposing sides of the module, connected to heatfins, much as you'd see on a laptops processors.
While the stock clockspeed of these units at DDR2-800 doesn't necessarily justify beefy heatsinks, OCZ has made their name on performance products that people love to overclock. Keeping RAM cooled is an issue that has only come up fairly recently in computing terms, but as clock speeds rise it becomes a more important one, especially since more manufacturers are willing to provide headroom for people to not just overclock, but also overvolt the units.
The new modules come in 2GB or 4GB kits. You can read the full press release at OCZ's site.