What hardware does Ubuntu Touch support?

Supported Devices

Nexus 4
Nexus 7 2013 WiFi
BQ Aquaris E4.5 (announcement)
BQ Aquaris E5 (announcement)
BQ Aquaris M10 (announcement)
Meizu MX4 (announcement)
Meizu PRO 5 (announcement)

Previously Supported Devices

Galaxy Nexus
Nexus 7 (2012)
Nexus 10

These devices have been deprecated and further development & updates may longer be available.

Porting to Other Devices

Directly quoting from the Ubuntu Wiki (obsolete URL removed!):

We want to port Ubuntu Touch to all kinds of devices. If you have experience in porting code to Android devices or are generally knowledgeable in terms of porting, working with the Kernel and other core bits and pieces of a distribution, this might be interesting to you.

Moreover, there's really no way to tell which future devices people will choose to work on, however there is a working list of devices that the community is working to enable here:

https://devices.ubuntu-touch.io/

Release Notes in the blog

Be sure to check for Known Issues before you proceed.
And Device Specific Issues as well.

Applications Available

The Developer Preview comes with the following functioning applications:

Gallery

Phone (Dialler, SMS, Address Book)

Camera

Browser

Media Player

Notepad

Music app

Calculator

Weather app

Installing Applications

Download application from store. Supported Application can be found in App-Store!
Or you can use The SDK to create an application of your own.

Only for Evaluation

Quoting from Ubuntu Wiki (obsolete URL removed!):

The Touch Developer Preview project provides the open source code for enthusiasts and developers, to familiarise themselves with Ubuntu's phone and tablet experience and develop applications on spare devices.

It is currently work in progress and intended for enthusiasts who want to contribute testing and building the platform.
Further quoting from their Install page (obsolete URL removed!):

It does not provide all the features and services of a retail phone and cannot replace your current handset.

This process will delete all data from the device. Restoring Android will not restore this data.

So be sure to do a complete backup before venturing out.

Flashing the device

Head here for instructions on flashing your device.

What to expect after flashing

Shell and core applications

Connection to the GSM network (on Galaxy Nexus and Nexus 4)

Phone calls and SMS (on Galaxy Nexus and Nexus 4)

Networking via Wi-Fi

Functional camera (front and back)

Device accessible through the Android Developer Bridge tool (adb)

Daily use of the phone

Advanced usage