I didn't install anything and I just posted this with voice to text...
That makes sense. The voices are for text-to-voice. Voice-to-text doesn't need text-to-voice data files. If you had tried to do something that has audio feedback, you might have had less success.
I was prompted to download them the first time I tried to start Google Navigation. It dumped me to the Marketplace with the voice file download pre-selected, I clicked "install", it did its thing and Navigation was happy again.
I think some programs do a good job of prompting you to tell you the voice files are missing and either mentioning that you need to get them or sending you to the Market to get them. Others (like voice dialing) apparently just ignore it and pretend the voice worked or fail in other ways.
So, like the original post on the thread says, just go download the voice files as soon as the upgrade is complete to save yourself the potential headache of trying to use an app that is trying (and failing) to use text-to-voice. You never know when you might need it, and it's not that large a download.
Another tip: I find that setting the voice to "slow" speed rather than normal makes it far more understandable. Pico is not a very nice voice synthesis no matter what, but slowing it down at least gives me a chance of understanding it.
Or you can speed it up so you don't have to listen to it as long.
