Xiamen Airlines, based in Xiamen China, became officially a SkyTeam member airline on November 21, 2012. You can read SkyTeam’s official announcement of this here.
The carrier currently flies mainly within China and has few international routes (you can access Xiamen’s route maps here) including Kuala Lumpur, Singapore, Seoul and Taipei. According to the press release, the carrier has plans to start flying to United States, Europe, and Australasia once they have received the Boeing 787 airplanes on order.
You can already earn and redeem miles from SkyTeam member airlines on Xiamen and vice versa. The eligible fare classes for earning miles are dependent of the frequent flier plan you credit the miles to. The following is a chart for Xiamen mileage accrual for Delta’s SkyMiles members.
It is always good to have more alliance airlines. This helps with earning and burning miles within China and North/South East Asia that the Xiamen Airlines serves at the moment. You will receive the SkyTeam elite benefits like lounge access and Sky Priority when flying on Xiamen.