Portuguese and US Spanish added to the offline options, but are still the old low quality versions
Google's Text-to-Speech, the app that powers speech output on Android devices in a whole range of apps, was updated today to include higher-quality voice options for those who speak English. For those who have their phones set to U.S. English, you now have the option to download a "Female (high quality)" voice that takes up a nice 244MB chunk of space on your phone and replaces the standard 6.8MB package. For those using U.K. English, you'll have a new Male option that's just 3.7MB, along with a Female (high quality) 276MB and Male (high quality) that's 100MB.
If you don't mind using up the space, it's a few simple steps to download the new voice data for a better voice output experience. The Text-to-Speech options can be found in Settings > Language & input > Text-to-speech output. You can then tap the settings button and hit "Install voice data" to pull down the voice packages that are useful and relevant to you. The data will only download over Wifi by default, and you can hit the trash can next to each installed voice package to delete it if you don't want it taking up space any longer.
The Text-to-Speech update to version 3.0 also includes both Portuguese and U.S. Spanish as options, but they're still the standard quality voices at 4.5 and 6.8MB, respectively.
Considering that the new high quality voices are dozens of times larger in file size over the default ones, we can't say there's a dramatic improvement in the quality of the speach output in our testing. The voices are quieter and a bit less choppy, and the 200-something megabytes it'll cost you on your phone are probably still worth it. By default the voice packages will be updated automatically as new data becomes available. This is one you'll be glad you installed, but you won't be blown away by the quality just yet.