The Shardminds of the 4e's PHB3 do remind me of one particular monster from PSMCIII, that being the Tsnng of the Quasi-Elemental Plane of Mineral. Now while I know they are conceptually quite different from each other, Tsnng being a bunch of natives of Mineral, and Shardminds being fragments of the Gate to the Far Realm. I see it as being quite possible, for using Shardminds to represent Tsnng, not that I ever saw anyone really wanting to play one.
Though they seem to match up in general appearance, I know their abilities don't quite match up, and I don't think any of the Tsnng's abilities back in 2e were ever meant as PC material. But I guess you could replace the Shard Swarm ability with some ability to increase the next attack by a bunch of psychic damage, but that just doesn't seem all that interesting compared to the Shard Swarm Power (which is to explode into a bunch of crystalline shards and reform a few squares away).
If you want they can be the same race, an offshoot of each other, or something completely different as far as the story goes. Who knows, maybe there was a gate to the Far Realm on the Plane of Mineral, or maybe it's where a certain collective of the Gate's living fragments is trying to rebuild the gate. Maybe the Tsnng are Shardminds, and they just don't care.
The Tsnng might need a bit more elaboration beyond their Monstrous Compendium entry, since all we know of them is that they see themselves as the self appointed rulers of the Plane of Mineral. Perhaps it's something to think more on whenever we get to renovating the Plane of Mineral. They're more interesting than the Bzastra from that same book, that I'm sure everyone has forgotten about.
And I don't think that the motivations of the Tsnng run counter to their motivations if they were Shardminds. The thing about Tsnng ruling small enclaves as the supposed overlords of their plane, who seek to destroy other enclaves. It's much like how some Shardminds seek to destroy other Shardminds, as they believe it might help rebuild the Living Gate. There's some cosmetic differences between the two. Obviously they changed the focus from arcane magic to psionics, mainly because of the crystals and psionics association built in 3e by Cordell who's probably behind that race.