It’s no secret that Yahoo! has two different photo sites. And two different social bookmarking sites. Until pretty recently I thought this was craziness. But gradually I’ve realized the power of this approach.
You take a smaller, hipper embodiment of an idea alongside a mainstream site. The resulting double-threat can’t easily be matched be either fresh startups or entrenched players. The smaller site can keep innovating and experimenting away, while the larger site adopts the best ideas and keeps improving without freaking out their base. It’s effective. Car companies have known this for years.
Now, my second realization: The W3C is doing the exact same thing with XHTML 1.x and XHTML 2.x+XForms. -m