Sweep;
I'm not a Health Care worker, but I don't believe that the vaccination is anything to be concerned about. Up until 20 years ago, every school child had to have the vaccination in order to go/remain in school. Just about everyone over 30 years of age has had the vaccination. It was about 15-20 years ago that they deemed the disease eradicated and ceased the immunization program, although I think they still immunize you if you join the military.
With that many people being immunized, I'm sure that there were a few instances of 'hyper-sensitivity' that caused injury/death, but from what I remember, the incidence was extremely low. I believe it was even lower than the incidence of getting polio from the polio vaccine (when they used the live virus), or Diphtheria, tetanus or pertussis from getting a DPT shot.
My guess is that you have more chances of getting smallpox from a terrorist than from the vaccine itself.
As for the smallpox concern being put to rest years ago, yes it was...but times obviously have changed. There were only 2 know sources for Smallpox...the CDC and the old USSR. With the unknown source of the recent anthrax attacks, it would seem that either of these sources could (or have) be(en) compromised.
I guess it comes down to odds and what you believe.
If you think that she/you may come in contact with the virus...get the vaccine and take your 1-in-1,000,000 chance that you/she has a reaction to the vaccine.
But remember, if you/she do come in contact with the virus, it is HIGHLY contagious and if the disease is contracted, there is a 30% fatality rate.
My guess is that the vaccination will be mandatory if your wife is one of the health care professionals that they deem vulnerable, although I suspect they will concentrate on emergency room personnel, EMS service, fire/police types, at least to start. Nothing could be worse than for one of these people to get the disease and pass it on to hundreds/thousands of others before they are diagnosed and become disabled.