I'm a Noob to SR4, but I noticed the term Psychotropic IC a few times in the SR4 book, and a lot more in the SR3 flavor stuff I've been reading.
What were the rules for it in SR3? Is it different than Black IC? Is it likely to reappear in the Wireless Matrix book?

Black IC could kill with simsense, but that was pretty much it's only trick until Psychotropic IC came along. Psychotropic IC could knock you out and reprogram your mind to varying extents. A particularly ugly one called Judas would cause you to subconciously betray your teammates.

Psychotropic IC is a sub-form of Black IC. "Normal" Black IC simply tries to "fry" or "destroy" your brain. Psychotropic IC tires to alter your brain in some shape or form. The rules for Psychotropic IC for SR3 were in the book Matrix iirc. There are a few different "flavours" of Psychotropic IC. These are the different kinds that I can remember without the book in front of me:
Matrix Phobia - the victim develops a phobia to the Matrix and becomes extremely agitated and even violently ill when inside
Judas - the victim feels a compulsive need to tell the truth, and to brag about everything that they have done
Loyalty (forget the "real" name for this one) - the victim now feels a deep loyalty to the company/organization running the IC and will no longer have any motivation to harm them

That's all I remember right now. Maybe someone with the book can add to this.

I think the rules are in Cannon Companion, for SR3. They function somewhat like personality fix BTLs, only more permanent.

Yep, though the effects are not +x to this -y to that. They were just "+a/b" to all TNs while using.

Judas was more subtle than that. The character would go along with life as normal, doing runs, killing people, and the like... but he'd have a subconcious compulsion to leave behind notes or evidence leading authorities towards himself and his group. Often times this kind of thing wouldn't even be remembered by the Psych-ICed person... he'd be the last one out of a hotel room, not remembering writing where they were going on the mirror, or he'd forget to disconnect until after the Trace IC had pinpointed the group's physical location.

Loyalty could also cause the character to want to buy products from that company. If your decker ever starts stockpiling, say, Ares Predators, you might want to ask him why. There was also some reference to someone who couldn't "keep it hard" unless he had a big glowing Fuchi logo somewhere in sight...

I believe there was a 4th type, but can't remember it. Actually, "glowing Fuchi logo" syndrome might have been the 4th type...

Matrix p108 describes Cyberphobia, Judas syndrome, Positive conditioning (Loyalty), and Frenzy. (But left it to the GM to invent all sorts of fun psychotropic IC of their own).
There was also Cerebropathic Black IC, which generated SR3 'stress points' to intelligence, willpower or an implant. Stress points are described in Man & Machine, but I don't have my copy of that at the moment and I can't remember the details.

Moving a bit off topic here, one of my biggest issues with SR3(and earlier, but it really proliferated in 3rd ed) and one that hopefully won't be repeated in SR4 was the cross referencing of obscure mechanics from the rules area focus books, like the stress points being mentioned in Matrix but refering to a rule in Man & Machine. I habitually buy almost everything Shadowrun published so that wasn't an issue, but having to carry half my collection just for rules reference got a bit inconvenient, not to mention the volume of sticky note page markers got ridiculous after a while.

I was just thinking the same thing.

There was an adventure "framework" in the Corporate War campaign called "Loose Lips Fry Chips." In it a "Decker friend" of one of the PC's got hit with Judas psychotropic and that's how they described its behaviour.

And they're searchable, which is a big plus. Not so good for bed-time reading, though.