Mozilla has announced an important update about the version number of the upcoming beta release of Firefox for Mobile (Fennec). The next release, Fennec 2.0b1, will be marked as “Firefox 4.0b1 for Android & Maemo” and the final product will be released as "Firefox 4.0 for Android & Maemo". The reason behind this jump in version number is to more closely match desktop releases of Firefox.
According to Mozilla blog, this change will not affect any user-setting or add-on compatibility, as the add-ons will be automatically marked compatible with the version 4, if they are marked as compatible for Fennec 2.0b1pre. Mozilla says, “We are aligning mobile Firefox and desktop Firefox since the web rendering engines used in both browsers are the same. Treating them as the same version seemed like the right thing to do.”