Someone was mentioning knockback happenning with Blazing Bolt with their Sentinal a couple days back.
I couldn't reproduce any knockback with my Blaster (but then, that power is different in the Blaster Fire set)
I tried it on Beta, didn't reproduce though I'll try again. Ok, this time reproduced fine on a level 50 sentinal.
Rolled one up to level 20 in Live and in an AE test, noted that Blazing Bolt seems to have a very probable chance for knocking an enemy back.
Tried again outside of AE and happens there as well. No enhancements in the power either.