pretty much what it says, blazing speed to move to replace scorch, new talent to replace where blazing speed was, which is Flameglow which is a flat damage reduction based off spell power up to 30% of the hit. Scorch to become fire baseline.
NOTE: This is a ptr experiment according to GC so don't go all end of the world... yet...
I think its an interesting change, makes the 2nd tier more interesting and removes scorch from being taken in most situations.
I, for one, have absolutely no doubt that Arcane, as an entire spec, in both PvE and PvP is going to end up in the toilet throughout the entire MoP expansion. You can bookmark this post, screenshot it if you wish, but you will see that that statement of mine will stand the test of time.