On the other hand:
Research and Development (R&D)-
This is the Corporation’s draw deck. R&D is kept facedown within reach of the Corporation. Cards in R&D are inactive.
And that doesn't keep Snare! from working while it is in R&D. The thing is that all of the other Ambush cards need advancement tokens, which they're not going to have in Archives (or R&D or HQ, for that matter).
Khudzlin is correct. Cards being inactive in the Archives is irrelevant when we are talking about Ambush cards such as Snare, Aggressive Secretary and so on.
Take a look at the rules on page 6 under Remote Servers.
"Cards in remote servers are active if rezzed and inactive if unrezzed."
We have already had confirmation from Lukas that ambush cards installed in servers do not have to be rezzed before the runner accesses them to take effect. The text on the card (When the runner accesses…) is what allows this. So we know that ambush cards still take effect even if they are technically inactive when the runner accesses them.
So if Snare is accessed in R&D by the runner, he WILL suffer the effects on the card if the corp pays the credits for it. Of course, Snare also states that if the runner accesses the card from R&D, he must reveal it. It does not say that the card takes effect even if it is accessed from R&D, because it does not have to. Ambushes can and will take effect even if they are inactive. The only reason the Archives is safe, is because all of the current ambush cards either need advancement counters to work (no advancement counters in the Archives) or because the card actually specifies that it does not work if accessed there (Snare!).
The end result is the same, but it is NOT because the cards are inactive. Keep in mind, this only applies to ambush cards because they have the text, "When the runner accesses this card", which Lukas has confirmed…..somewhere on BGG. This means that there is room in future expansions for an ambush card that works from Archives as well.