Are you referring to reciprocal linking? (You link to Site A, and Site A links to you?)
Or are you going to do a 3 or 4 way exchange?
I'm no expert, but here are my two cents...
In the reciprocal 2-way linking case, Google and other search engines can easily see what your doing. While it used to be a great strategy for links, the search engines have really smacked down the value of those links because they are so easy to get.
My theory is to trade links with a site only if it is really relevant and complimentary to mine. Basically, I do it for the value of the traffic it can send alone, rather than worrying about PR and Ranking.
For the second case, it might work out. I don't know. Kind of like my approach above, I try to go for relevant links that will stand the test of time. If you are doing a link exchange and you are getting links from completely unrelated sites, you probably won't get traffic, but if its an authoritative page you might get some juice.
The main concern should be who you are linking to. Google can't really penalize you for getting linked to, since you have no control over that, but you do have control over who you link to. "Don't link out to bad neighborhoods" is what they say these days. Make sure you check both where you might be getting a link from, and more importantly, who you are linking to.