The feat Alacritous Cogitation says the following:
If you leave an arcane spell slot open when preparing spells, you can use that open slot to cast any arcane spell you know of the same level or lower and of casting time no longer than 1 round. Casting the spell requires a full-round action. You can use this feat only once per day, regardless of the number of slots you leave open.
Does this count as Spontaneous Casting for the purposes of, for instance, the Practical Metamagic feat?
From the description of Alacritous Cogitation (Complete Mage p. 37):
You can leave a prepared spell slot open to spontaneously cast a spell.
This is from the summary section of the feat, not the section marked "Benefit," so there's some room for interpretation about whether this sentence has the full weight of rules text...but it's pretty clear, and since the "Benefit" text is ambiguous anyway, I think it's the clearest indication you're going to get on this one.
No one knows.
“Spontaneous” spellcasting is never defined in the rules. In fact, the only class features in the game to actually refer to themselves as “spontaneous” spells are the cure and inflict of clerics, the summon nature’s ally of druids, and similar—cases where normally-prepared spellcasters get a little bit of spontaneity. The word “spontaneous” does not appear in the spells class feature of bards, sorcerers, and so on.
Instead of being defined, the concept of spontaneous spellcasting was left as “I know it when I see it,” which is probably fair in 99% of cases but corner cases like Alacritous Cogitation and even the actual spontaneous spells features of clerics and druids leave people scratching their heads.
In short, ask your DM. In most cases, burning a feat is probably fair cost to count, but I could see situations where that wouldn’t fly with me, because I want whatever to be special for spontaneous casters—and Practical Metamagic might be one of them, for me.
