I am looking at a air-pwrinj4 for a 1252 right now and there are no speed indicators on the rj-45 jacks and there is no mention of it on the url:

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps6973/ps8382/product_data_sheet0900aecd806b7c5c.html

Come to think of it, I don't recall seeing any speed rating on any other power injectors in the past.

Chances are, it is such a low level device,that does not affect speed significantly. It should only put power on the proper pair and just past the other pairs thru.

wouldn't that be a hoot if the power injector was rated for only fast ethernet!