Simply put, Pinnacle is the high-level campaign that we're currently trying to get under way. It starts right where the Player's Handbook ends and just before the Epic Level Handbook begins - at that magical 20^th level. Adjusted by ECL and what have you, of course.

The campaign takes place in an alternate cosmology, a cosmology where planar travel is slightly more difficult than just plane shifting wherever one wants to be. In this cosmology, certain planes - or shards, to borrow the Pinnacle terminology - contain 'sweet spots', geographically precise locations where it is easier to travel to other shards. Naturally, these sweet spots - called shardways in Pinnacle - are highly contested areas, considering their strategical importance.

Of course, many never divine the presence of shardways on their shards, and thus are ignorant of the bigger picture. Others know of them, but ignore them. And others, yet others, try to exploit them in multi-dimentional chess games.

Pinnacle is the center shard - or, at least the Pinnacle shardlore considers it to be the center shard, considering that Pinnacle has the most shardways of any shard. Thus, Pinnacle is the real estate to control if one has designs on traveling to other shards - for sightseeing, knowledge, or that old time favorite... world domination.