Thanee
First Post
I don't think it does. Some PrC in Complete Arcane specifically mention spell-like abilities (i.e. the Mindbender); it's pretty unlikely, that they made a rule that invocations count as spells in terms of PrC prerequisites, if they do that in the very book they are printed in.
In fact, it actually even says, that they don't count as spells.
Bye
Thanee
In fact, it actually even says, that they don't count as spells.

Bye
Thanee