It seems like many flavours of datacenter ethernet are settling down! Couple of years ago, there was 10Gbps x 4 and 10Gbps x 10 for 40Gig and 100Gig ethernet, some what influenced by the legacy InfiniBand camp. I am glad to see 25Gbps getting the approval of the majority.
We did have healthy discussions around 25/28gig SerDes couple of years ago after OIF / CEI standard for 25G class designs was approved:
There are certainly specific issues, complexities, and challenges of moving to 25G or higher, and I'm glad to see this decision by IEEE. For futher reading/info: Steve Tarnovich at EDN posted an article on 100GbE recently, and this is a major topic that we deal with at DesignCon.