uuhhmmm...yes he was...and he was talking to "Dr. Shaw" who is..guess who??
You can hear his name being mentioned by Hank but you can never his face.
http://www.angelfire.com/moon/daehkcid/x01.jpg
Gambit was also in there if you don't know yet. At least his name was in it, as well as the other mutants'.
http://www.angelfire.com/moon/daehkcid/x2a.jpg
Guthrie, Paige (Husk)
Guthrie, Samuel (Cannonball)
Harada, Keniucho (Silver Samurai)
Kane, Garrison (Weapon X)
LeBeau, Remy (Gambit)
Lensherr, Eric M. (Magneto)
Madd!cks, Arthur (Artie)
Madrox, Jamie (Multiple Man)
Mahn, Xi'an Coy (Karma)
Maximoff (2) These are supposed to be Pietro and Wanda
Munroe, Ororo (Storm)
http://www.angelfire.com/moon/daehkcid/x2c.jpg
Omega Red, (a Russian supersoldier)
Muir Island, (Scottish laboratory)
Project Wideawake (Sentinel Program)
Franklin Richards (Fantastic Four's Reed Richards and Sue Storm's son, born a mutant)
Cerebro
http://www.angelfire.com/moon/daehkcid/x2b.jpg
See! Even Bryan Singer has his own subtle cameo!
These are just all the subtle cameos, I suppose you already know that Siryn, Shadowcat and Colossus had their own in-your-face cameos.