To paraphrase the first line of Infusions on the Artificer class:
The Artificer isn't a spellcaster, but it can imbue items with magical infusions.
Unfortunately the Eberron Campaign Setting isn't OGL, or I would quote you directly. Either way, Artificers ARE NOT spellcasters. This is why the class description then goes on, at some great length I might add, to list all the ways Artificers are like spellcasters. They can't even use spell completion items for free if they contain a spell appearing on their infusion list, it's UMD all the way, because they're different. Later it explains how can can still use meta-magic on your infusions (like a sorcerer), because strictly it wouldn't be possible otherwise, the stipulation is all in the first line.
I would like to know the general consensus on this issue actually, I've debated with fellow DMs in RL at home for considerable time, and we don't see any other good way of interpreting this.