This is difference between the default preference of Firefox 10-beta2 and one of 9.0.1.


Default pref Javascript files:
(omni.jar){/greprefs.js,/defaults/pref/{firefox.js,firefox-branding.js,firefox-l10n.js,services-sync.js}}

PrefFirefox 9.0.1Firefox 10 beta 2
browser.link.open_newwindow.override.externalundefined-1
devtools.editor.componenttextareaorion
devtools.gcli.enableundefinedfalse
devtools.inspector.enabledfalsetrue
devtools.inspector.htmlHeightundefined112
devtools.ruleview.enabledundefinedtrue
devtools.styleinspector.enabledfalsetrue
dom.battery.enabledundefinedfalse
dom.ipc.plugins.parentTimeoutSecs015
dom.new_bindingsundefinedtrue
extensions.getAddons.search.urlhttps://services.addons.mozilla.org/%LOCALE%/firefox/api/%API_VERSION%/search/%TERMS%/all/%MAX_RESULTS%/%OS%/%VERSION%?src=firefoxhttps://services.addons.mozilla.org/%LOCALE%/firefox/api/%API_VERSION%/search/%TERMS%/all/%MAX_RESULTS%/%OS%/%VERSION%/%COMPATIBILITY_MODE%?src=firefox
extensions.minCompatibleAppVersionundefined4.0
extensions.minCompatiblePlatformVersionundefined2.0
extensions.strictCompatibilityundefinedfalse
extensions.update.urlhttps://versioncheck.addons.mozilla.org/update/VersionCheck.php?reqVersion=%REQ_VERSION%&id=%ITEM_ID%&version=%ITEM_VERSION%&maxAppVersion=%ITEM_MAXAPPVERSION%&status=%ITEM_STATUS%&appID=%APP_ID%&appVersion=%APP_VERSION%&appOS=%APP_OS%&appABI=%APP_ABI%&locale=%APP_LOCALE%&currentAppVersion=%CURRENT_APP_VERSION%&updateType=%UPDATE_TYPE%https://versioncheck.addons.mozilla.org/update/VersionCheck.php?reqVersion=%REQ_VERSION%&id=%ITEM_ID%&version=%ITEM_VERSION%&maxAppVersion=%ITEM_MAXAPPVERSION%&status=%ITEM_STATUS%&appID=%APP_ID%&appVersion=%APP_VERSION%&appOS=%APP_OS%&appABI=%APP_ABI%&locale=%APP_LOCALE%&currentAppVersion=%CURRENT_APP_VERSION%&updateType=%UPDATE_TYPE%&compatMode=%COMPATIBILITY_MODE%
full-screen-api.enabledfalsetrue
full-screen-api.warning.enabledundefinedtrue
html5.parser.enabletrueundefined
intl.accept_charsetsiso-8859-1,*,utf-8undefined
javascript.options.tracejit.chrometruefalse
javascript.options.tracejit.contenttruefalse
layout.3d-transforms.enabledfalsetrue
network.http.fast-fallback-to-IPv4falsetrue
services.sync.jpake.lastMsgMaxTriesundefined300
services.sync.log.logger.statusundefinedDebug
webgl.disable-extensionsundefinedfalse
webgl.min_capability_modeundefinedfalse
webgl.msaa-forceundefinedfalse
webgl.msaa-levelundefined2