It hasn't, still listed as a CB on the site.

Not that it matters, he might be playing QB for all he knows since no one actually talks to the players.

Phillips is very impressive when healthy but he has been fighting injuries over the last few years, however if he has done a good job rehabbing over that time he might be healthy in 2015. Phillips is a true SS that plays coverage very well also, he is a very well rounded player.

Assuming health is not an issue here is what the 2 and 3 Safety sets should look like next year:
Two set:
FS:Byrd
SS: Phillips

Three set:
FS: Byrd
SS: Warren
S/NB: Phillips

Vaccaro might be better suited to play CB since a lot of his time in college and in 2013 was covering the slot WR. Last year Vaccaro even matched up against guys like Steve Smith and Vincent Jackson so perhaps the solution to our #2 CB spot is there, maybe...

At this point I think it's clear the team doesn't think Vaccaro is the best option at Safety, I just hope this isn't yet another defensive draft bust.

Here are some highlights of Phillips for those of you who have not seen him play:
Kenny Phillips highlights - YouTube