8 years later and this is the first time I've heard of it -- doesn't seem to have caught on in the US (at least not at the consumer level)

It only exists at the consumer level as a novelty.

You can get chewable tablets labelled "mberry", places like maybe Spencer's Gifts or similar tchotchke merchants.

They're a fun small gift but I think their use as a sweetener is limited due to the way it changes other flavours.

I had the opportunity to taste this berry where I live (French Polynesia) and indeed very surprised by its powerful sweetening effect. It looks like an under-exploited potential to me.