All of a sudden we're hearing a fair amount about Bella Sara, the trading card game with a virtual world component. Featuring pretty horses and unicorns, it's targeted at young girls. Last week, we reported that Bella Sara's parent, Hidden City Games, raised $15 million from Rustic Canyon Partners and Trinity Ventures -- two VCs who are fans of virtual worlds. Right now, Bella Sara cardholders can play with a virtual horse online unlocked by their card's code, but they can't trade or play with their friends' horses.

The New York Times looked at the Bella Sara phenomenon and talked to Hidden City founder Peter Adkison, who's already seen success with Magic the Gathering cards, distinctly preferred by boys, and unisex Pokemon cards, and discusses the challenge of making this product specifically for the gals:

The cards, called Bella Sara, are clearly more girl-friendly than the latest set of hockey cards or Dragon Ball Z cards. They have pastel colors, fanciful pictures of unicorns and virtual horses to groom, along with girl-power sayings like “Have the courage to trust yourself” and “Use your love to bring peace to the world.”

But history is against Mr. Adkison. “Is it possible a trading card product could catch on primarily with girls?” said Alan Narz, a columnist for Card Trade magazine. “Yes. Has it ever been done? No.”

There are challenges other than history. Bella Sara cards are not used as part of a competitive game, where having a rare card can mean the difference between triumph and defeat.

Whether or not Bella Sara launches a "true" virtual world (though with the unlockable online horse interaction, it definitely falls into the sphere of relevance) it looks as if there will be some interesting lessons to be gleaned about digital toys for girls.