The problem is, that espeak is in an inconsistent state in the extras repository. [1]
The newest version of the espeak package there is 1.46.22, while for its dependencies espeak-data and libespeak the newest version is 1.46.27. espeak needs exact version matches for its dependencies, but since apt-get tries to install the most recent version, this creates a conflict that can't be resolved.

dirty stopgap:
A: Manually download and install the three packages in version 1.46.22.
B: Install espeak from extras-devel, where espeak is in a consistent state. [2]

actual solution:
Whoever feels responsible for it needs to put espeak in a consistent state in extras.

Edit:
Take this warning: You should expect problems like this one a lot when installing software in Maemo.
In case you're familiar with Debian or one of its derivatives (Ubuntu, Mint, etc.) you might have gotten the tip to always double-check, what apt is going to do. While on Debian it is usually safe to ignore that tip, here it isn't! Maemo WILL try to cross you.


[1] http://repository.maemo.org/extras/p...free/e/espeak/
[2] http://repository.maemo.org/extras-d...free/e/espeak/