First off, let's look at the bigger context. I see this stuff as someone who has followed Apple pretty closely for the last 10+ years and I guess I expect others to attempt to see it in that context too, not isolate it to only the last year.
Apple's update cycle for computers, especially the consumer-level stuff has dropped off sharply while all their activity lately seems focused primarily on the iPhone and to a lesser extent, the iPod. To me, after having gone through the old days of frequent updates and seeing that drop off to 11 months at a time, well... that's close enough to a year from my viewpoint. If you want to split hairs, fine, but there's no denying that Apple appears to be shifting into a yearly update cycle.
Second, you're downplaying what I'm saying by using only the current cycle. The previous update was close to a year. As it stands, the iMac and the Mini are 9 months past their last updates. A few years ago, that would have been unthinkable. We would have seen a price drop or a specs bump around 4-5 months and would be talking about what's coming up next month or sooner. Nowadays, nothing.
Third, I think it's pretty safe to say that Apple likely won't be updating the iMac or Mini until late summer or later. If they've waited this long, what's the rush? And from what I see, the two are probably selling well enough.
It's unfortunate that Apple is going to let the computers lag at a time when consumers are really interested in Apple's machines. They should be trying to blow people's minds with the consumer-level stuff, but it's just withering on the vine.
software update. 
