IMO: That wasn't a slide. Utley threw himself at Tejada's legs. Heat of the moment - playoffs, looking to tie the score, etc. - it's a play every player is taught to make, go in hard, take out the turn, break up the double play. The only place where "a slide shall be deemed appropriate" is in rule 7.13(1)c comment about the play at the plate. Otherwise, you won't find the definition of a "slide" in the MLB rule book, although the FED (high school) rule book has it.
Regardless of how we feel about the result/aftermath, it's an "accepted" baseball play in MLB even though through HS and College it's not. I guess it's felt a grown man making a living off the sport should be "OK" with the play. The fact that the out at 2B got overturned is odd since if Tejada didn't touch the bag and Utley didn't touch the bag before running off the field, then how do you award him 2B when he abandoned his effort to touch the base before running off the field?
As for retaliation - you don't think MLB hasn't said something to the Mets? I don't see retaliation this year, because whomever retaliates is going to be suspended and then where does it end? I would also not be surprised to see an umpire call an out on a similar play from here on in.