The Synthesia “Open Synth Hardware Platform” uses a Gumstix board, FPGA chip to create a anaolog modelling synthesizer with touchscreen interface –

The synthesia platform is a project whose purpose isto create an Analogue modelling musical synthesizer; that is, a synthesizer implemented using both analogue and digital components that intends to emulate the sounds of traditional analogue synthesizers, whilst being controllable through modern-day digital protocols such as the Musical Instrument Digital Interface (MIDI).
The synthesizer platform exists upon it’s own standalone hardware, and may be controlled using a variety of existing MIDI-capable instruments, including keyboards, guitars and drums.
Additionally, the unit features it’s own innovative touch-screen interface which intends to
provide simple-and-intuitive control of the system, but with an unprecedented ability to
customize and control synthesizer parameters and sound generation.
Special attention has been placed upon the usability of the synthesizer, particularly within the realms of it being played by musicians in a live environment.
The unit’s MIDI capabilities also mean that it is easily combined with professional studio
equipment and sequencing software such as Cubase VST

Synthesia hardware overview