It's available from the usual places - if you have an official Espruino Board you can use the Web IDE's update feature, and with Puck.js you can use a phone: http://www.espruino.com/Puck.js#firmware-updates
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
I've just released 1v92 - it's been a while coming, but there are now a huge amount of new features:
Pin.toggle()
, eg.LED1.toggle()
Fix precedence of 'void' keyword (#1079)
Pico/WiFi: Allow USB HID to work on Windows (from @nailxx)
Puck.js: Now use 'high drive' mode for GPIOs - provides much more power output on pins
Puck.js: tweak IR duty cycle, with high drive GPIO the Infrared range is now ~3x more
Puck.js: Allow Puck.IR to take pins for an external IR LED (#927)
Puck.js: Allow arbitrary NFC data to be specified (#1021)
Puck.js: Allow multiple advertising packets to be set at once with NRF.setAdvertising
Puck.js: Add 'properties' object to BluetoothRemoteGATTCharacteristic
Puck.js: Perform BLE write without response if that is what is required
Puck.js: Add BluetoothRemoteGATTCharacteristic.startNotifications (#959)
Puck.js: Added BluetoothDevice.gattserverdisconnected event
Puck.js: Report back reason codes for BLE disconnect
Puck.js: char.readValue now returns DataView to be more Web Bluetooth compliant (#1091)
Puck.js: Respond to conn_params update request, fix puck-puck disconnection after ~65 sec (#1089)
Puck.js: Change connection params for central mode so NRF.setLowPowerConnection affects connection speed
Puck.js: Correct reading if using analogWrite to red LED and then using Puck.light()
Puck.js: stop app_timer NRF_ERROR_INVALID_PARAM errors (trying to sleep for too little time)
Puck.js: Don't get stuck in 'HID Busy' state if a HID send failed
Puck.js: Allow services to be advertised (fix #996)
ESP8266: Add Wifi.setAPIP() and Wifi.setIP
ESP8266: Add i2c clock stretch (#1097)
ESP8266: Add ESP8266.deepSleep(micros, option) (#1102)
It's available from the usual places - if you have an official Espruino Board you can use the Web IDE's update feature, and with Puck.js you can use a phone: http://www.espruino.com/Puck.js#firmware-updates