Speaking with PC Gamer, Mass Effect 3 executive producer Casey Hudson revealed that Tali'Zorah vas Normandy will return as a full-time squad mate in the third and conclusive entry of the Mass Effect trilogy.
In addition, he also confirmed that "everyone's that's a main character is in Mass Effect 3," although not necessarily as a squad member, such as Wrex. Other squad mates include Garrus, Liara, Ashley or Kaiden, and James Vega.
Mass Effect 3 was recently delayed into the first quarter of 2012. It'll be out then on PC, PS3 and Xbox 360.
Source: PC Gamer