WebSphere V9 "traditional" has recently been fully Java EE 7 certified. In case you are wondering, this is indeed the much maligned "kitchen sink" monolithic version of WebSphere—as opposed to the far more nimble WebSphere Liberty.
Given the very large and loyal customer base IBM has as well as the continued substantial usage rates for WebSphere traditional, this is sure to be a further boost to Java EE 7 adoption. In particular, it is important to note that WebSphere V9 also comes with support for Java SE 8.
You'll find the trial link for WebSphere V9 here. IBM senior staffer Tom Alcott has a nice technical write-up on the details of WebSphere V9 certainly including support on various cloud platforms including BlueMix. It should be noted that unlike WebSphere traditional, WebSphere Liberty was one of the earliest available commercial Java EE 7 certified application servers, certainly well ahead of WebLogic and JBoss EAP. You should really check out my WebSphere Liberty Java EE 7 compatibility announcement on The Aquarium, written while I was still at Oracle.
Other than for existing WebSphere traditional customers, it is honestly difficult to recommend it over WebSphere Liberty. Whatever you may think of the WebSphere brand, you will be doing yourself a disfavor if you do not take WebSphere Liberty seriously. You should definitely not let any open source prejudices unduly hinder your appreciation of the engineering work behind Liberty. It is absolutely one of the most modular, lightweight, and impressive performing (in every way) modern application platforms available today—Java EE or otherwise. Hopefully, that is food for some thought...