this is normal... and its totally ok for him to feel this way. theres nothing wrong with being "mamas boy" - it lasts such a short time, and other people (friends, other relatives, etc) seem to take up more time :(
a few things you should and should NOT do.
most definatly DO NOT SNEAK AWAY!!
this is scary for your son! he needs to know you are going to be gone, and that you will return. as much information as you can give him. but then be matter of fact about it, if you act like its no big deal, he will eventually also.
your husband NEEDS TO UNDERSTAND IT HAS NOTHING TO DO WITH HIM. he can NOT take this personally. its not about his child not wanting him, its just that your son wants you at that moment or whatever, and its hard for him to understand that you just need to ____ or whatever. the WORST thing he can do is be upset with your son because of this. what your husband needs to do is be given the time and the tools to figure this out on his own, with some gentle guidance. it is pretty easy to distract a child. find something your son really likes to do, and have dad start that project/game/toy/movie when you have to leave somewhere, so that hes doing his favorite thing with dad or something. have dad be proactive about having patience, giving it some time, and relaxing; your son can sense when you are upset, so hubby needs to take it easy. maybe its a meal time or something so that theres enough distraction and a way for your husband to interact positively with your son and you can do ___. try it once every day that you are able to do it. even if its just to go to the bathroom in the evening or something. take a bath or shower, read a book, do some exersizing.
my husband gets mad when brody throws a fit at him; my hubby's "job" is to get our son ready for bed. our son tends to throw a fit about it and hubby gets mad and throws a fit and/or gives up. this works every time so our son keeps doing it. he really just needs to remain calm, not take it personally, and stop being so defensive. this is a young child! a 2 year old! hes not doing it to spite your hubby, hes not doing it to make him mad, hes not doing it even to really get his way, just because hes upset and 2 year olds have a hard time expressing their emotions and wants and stuff.
anyway, this is a tough thing because hubbys for some reason get so personal about it. as if their kids just hate them or something. but like i said, find a positive thing they can do together, im sure your hubby can find something (my son LOVES to ride the lawnmower with my hubby! or check out a car engine or something ;P :P
anyway,
good luck