For-Seeker: but what do I need with the ICs? What kind of shield do I need to get this work for me?
OK sorry for muddling things, if you have a module or shield that's build around a voice synthesizer you don't need the IC (because it's already included). I specifically mentioned that type of IC to let you know they exisit and indicate that they are a different way to do what you want. Also, as johnwasser and I were discussing if you get a pre-made audio or voice synthesizer circuit it doesn't need
to be a shield, it would just be easier to find material to help you write a program to use it.
Or the best question would be: what things should I watch when I search for a good shield to get that kind of IC work for me?
For any project you should consider the function, and possibily form, you want for your eventual device.
In this particular case, if there are audio or video files available that demonstrate how well an electronics module either plays recordings or generates speech you should check them out. Also spend a little time searching both the Arduino forums and any affiliated with the organization you are purchasing from, to see any examples of what other people have done with that product as well as if there are any common or particularly vexing problems with it. Ultimately you want to find something that will do what you want it to, not take more time and effort to integrate in your design than you are willing to spend, and not just be effective but cost-effective as well. All these things can be very subjective, so while the boards I discussed and linked to would work in your project you will always be the one to determine what's "best".
Back to the "form" considerations... Since you are using the Lilypad I'll presume you want this to be a portable device, likely incorporated into a garment of some kind. As johnwasser pointed out, with the Lilypad the shield form factor has no innate advantage over a similar circuit on a different shaped PCB. If you can find a design not in a shield that is functionally the same or similar and has decent documentation and/or available Arduino libraries and/or examples, it wouldn't be a problem to use it instead of anything mentioned so far. In fact, if it is smaller it might be better for your particular application (again presumming it's intended to be portable/wearable).
Hopefully this reply clarifies things for you.