the 2003 investigation by the immigration dept. and RCMP in which there were allegations about the group of men being a 'sleeper cell' etc?
If I recall correctly, in that case, those guys were actually arrested on immigration violations as they had all purchased fake resident documentation from some illegitimate business school in Ottawa, and some clearly overzealous investigators made mountains out of mole hills in trying to make out that they were terrorists with plans to blow up the Pickering plant, etc. The "evidence" that led to those specious accusations was quite ludicrous.
I think you may be incorrect, though, about the men not being charged and about them being released. I don't think any of them were ever charged with terror-related offences, but I think that most of them were held on immigration violations and nearly all of them were ultimately deported.
This investigation differs on its face from the 2003 one, as it appears to have begun specifically re: alleged terrorist activity/connections and not an immigration investigation which tangentially went into the terror possibility realm, and these people have, in fact, been charged with specific offences.
Of course, we have yet to see the evidence upon which these arrests were made, and we are unlikely to see it all for quite some time.
Still, 3 tonnes of ammonia nitrate and various explosive devices were recovered, and so far, this investigation appears to be on the up and up. I do not, generally speaking, trust police any further than I can throw them (edit: at least not without verification), but they don't always get it wrong, either. That said, I would not be surprised if the net was too widely cast - it often is - and that some of those currently being held will ultimately be released. Then, of course, there is always the possibility that they will be ultimately acquitted at trial, too. It will all depend on the evidence, which none of us has seen yet.
http://www.theglobeandmail.com/servlet/story/RTGAM.20060603.wwarrants0603_3/BNStory/National/homeAnd about the photo of the bag of fertilizer, from all of the various news accounts online, it was specifically stated that it was for display purposes only (presumably because "three tonnes of ammonium nitrate, a commonly used fertilizer used to make explosives, were recovered by police, who say that’s three times the amount used in the bombing of a government building in Oklahoma that killed 168 people" and one 25 kg bag is a whole lot more convenient to photograph and a whole lot LESS frightening than photos of three tonnes of the stuff.