Finn Mayhew

From my experience, yes.

In 14w33a, it appears to be fixed.

http://www.mediafire.com/download/50d595kl9pbg8l1/TARDIS_2014.zip

There are spawners throughout.

I can record, upload, and link a short video of the effect if you'd like to see. I'm not sure I described it well.

I am using Jesper's XP Item clock. I went into the same world in 14w32a, and I'm still having the problem with every spawner in the world. Sometimes I'll be walking down a hallway and see spawner particles flying about.

For the spawner pictured,

setblock ~ ~-1 ~ minecraft:mob_spawner 0 replace {EntityId:XPOrb,SpawnCount:1,SpawnRange:1,MinSpawnDelay:1,MaxSpawnDelay:1,MaxNearbyEntities:32000,RequiredPlayerRange:10,SpawnData:{Pos:[2.5,102.0,8.5],Age:5999}}

I had been using piston extensions in the 1.8 snapshots and in 1.7 before this, though. It was only in 14w29 that they were removed from my world.

Me too, same version.