Singapore-based Kenny Lee, who writes the blog Tag Edge, points to a brief CNet China story from Tuesday reporting that Xiaonei, China’s largest (mostly) campus-based social network, has announced that it will open its platform on a Beta basis to third-party application developers.  (Big tip of the hat to David Wolf of Silicon Hutong for alerting me to the Tag Edge story!).

The SNS, which recently made news when Softbank Corp announced it would be leading a whopping $430 million investment in Xiaonei’s parent company Oak Pacific Interactive, has been ridiculed as a mere Facebook clone — the resemblance is indeed uncanny — but developers familiar with the platform had long ago told me that the site hadn’t been set up to accomodate third-party developers, and that a major revamp would be required before it could be made ready.

According to the CNet piece, applications developed for Xiaonei will be allowed to run in limited areas of the site — among user groups specific to certain campuses, for example — and will not be generally released. The Beta test phase will last about six months.

Tangos Chan wrote about the imminent announcement in a post on May 30 here,  which I somehow failed to see. Doh! He suspects that the “announcement,” which was in an employee’s blog post and not made formally, was a reaction to rival 51.com’s revelation that it would open its API. As has been reported recently, 51.com — China’s second-largest social network, which appeals to young users in lower-tier Chinese cities in contrast to the college-educated, white-collar elite youth courted by Xiaonei — said that it would open to third-party application developers in June.

This is, of course, excellent news to the embryonic widget industry here in China — companies like Guo Chunlong’s Yobo.com, which makes a music recommendation application that has already been developed for several blog service providers as well as for Open Social, where it’s now deployed on Friendster. But there will be real restrictions on the extent of Xiaonei’s openness, at least initially: According to one developer with whom I spoke, Xiaonei has deccided that slideshow applications, travel-related applications, and recruiting applications are going to be off limits to developers. That’s bad news for one excellent up-and-coming widget maker, Liu Yong’s Rekoo.com, which has a very slick, highly versatile slideshow application.