Details of recent changes. This extension is covered by the Mozilla tri-license apart from the AES and TEA implementations by Chris Veness, which are covered by LGPL.
Just click on the link below and the extension will be automatically recognised by Firefox and the installation process will begin. This same link can be used to upgrade an existing extension to the latest version. Once you reboot Firefox you'll notice that an 'S' icon appears in the status bar of your browser and you're ready to starting using it as described.
SyncPlaces Firefox Extension v3.3.0 (133kb)
Alternative download from Mozilla
Note that there is a known issue with Firefox extensions so that every now and then your browser will report them as being corrupted, or invalid. This can affect all extensions although there is actually nothing wrong with them. There are two possible solutions: Either clear your browser cache and try again, or right mouse click on the first link above, save the .xpi file to your computer, then drag the .xpi (or open it) in your browser and it will install as normal.