The Infonortics conference was great, starting back in the late-90s. It one of the places where old-line Information Retrieval people and new Web Search people and even site search people could mingle. I learned a lot from everything there, including some work on entity extraction and text mining that's only now in general use, (and some that never went anywhere: 3D immersive search results visualization, anyone?)
In most years, the Infonortics meeting was in Boston in April, while the Enterprise Search Summit was in New York in May: my travel budget and family could only handle one of those, and Nancy Garman let me help with ESS, so I chose that one.
The announcement doesn't have details, and I do hope the Search Engines Meeting, with its more theoretical flavor continues, or perhaps a track of it is incorporated into the Enterprise Search Summit.