The line between activism and marketing gets blurrier each time Earth Day rolls around, but here’s some corporate greening we’re happy to see.

W Hotels is launching a program where guests can take a Puma bike for a spin at no charge. Most W locations in the US and Canada will participate, the exceptions being in cities with more than one W. (In New York, this means two out of five Ws get bikes — the Union Square and the Court.) Each hotel will have two bikes available, which may not seem like many, but it sure beats zero bikes. The offer will last at least until the end of 2008, and it may continue if interest is strong enough, according to a W spokesperson.

Come 2009, who knows, maybe we’ll see four bikes per hotel.