This is difference between the default preference of Firefox 11-beta1 and one of 10.0.

Default pref Javascript files:
(omni.jar){/greprefs.js,/defaults/pref/{firefox.js,firefox-branding.js,firefox-l10n.js,services-sync.js}}
PrefFirefox 10.0Firefox 11 beta 1
browser.cache.compression_levelundefined0
browser.dom.window.dump.enabledundefinedfalse
browser.fixup.use-utf8undefinedfalse
capability.policy.default.Navigator.preferenceallAccessundefined
capability.policy.default.Navigator.preferenceinternal.getUniversalPreferencesReadundefined
capability.policy.default.Navigator.preferenceinternal.setUniversalPreferencesWriteundefined
config.use_system_prefsfalseundefined
config.use_system_prefs.accessibilityfalseundefined
devtools.styleeditor.enabledundefinedtrue
devtools.tilt.enabledundefinedtrue
devtools.tilt.force-enabledundefinedfalse
devtools.webconsole.filter.csserrorundefinedtrue
devtools.webconsole.filter.cssparserundefinedtrue
devtools.webconsole.filter.errorundefinedtrue
devtools.webconsole.filter.exceptionundefinedtrue
devtools.webconsole.filter.infoundefinedtrue
devtools.webconsole.filter.jswarnundefinedtrue
devtools.webconsole.filter.logundefinedtrue
devtools.webconsole.filter.networkundefinedtrue
devtools.webconsole.filter.networkinfoundefinedtrue
devtools.webconsole.filter.warnundefinedtrue
dom.battery.enabledfalsetrue
dom.ipc.plugins.processLaunchTimeoutSecs4525
dom.ipc.plugins.timeoutSecs4525
dom.sms.enabledundefinedfalse
dom.sms.whitelistundefined
dom.vibrator.enabledundefinedtrue
dom.vibrator.max_vibrate_list_lenundefined128
dom.vibrator.max_vibrate_msundefined10000
extensions.getAddons.get.urlhttps://services.addons.mozilla.org/%LOCALE%/firefox/api/%API_VERSION%/search/guid:%IDS%?src=firefox&appOS=%OS%&appVersion=%VERSION%&tMain=%TIME_MAIN%&tFirstPaint=%TIME_FIRST_PAINT%&tSessionRestored=%TIME_SESSION_RESTORED%https://services.addons.mozilla.org/%LOCALE%/firefox/api/%API_VERSION%/search/guid:%IDS%?src=firefox&appOS=%OS%&appVersion=%VERSION%
focusmanager.testmodeundefinedfalse
font.allow_double_byte_special_charstrueundefined
font.size.inflation.emPerLineundefined0
font.size.inflation.minTwipsundefined0
gfx.font_rendering.graphite.enabledundefinedfalse
hangmonitor.timeoutundefined0
intl.hyphenation-alias.de-AT-1901undefinedde-1901
java.default_java_location_others/usr/javaundefined
java.default_java_location_solaris/usr/j2seundefined
java.global_java_version_file/etc/.java/versionsundefined
java.java_plugin_library_namejavaplugin_ojiundefined
java.private_java_version_file~/.java/versionsundefined
javascript.options.jit_hardeningundefinedtrue
javascript.options.jitprofiling.chrometrueundefined
javascript.options.jitprofiling.contenttrueundefined
javascript.options.tracejit.chromefalseundefined
javascript.options.tracejit.contentfalseundefined
layers.offmainthreadcomposition.enabledundefinedfalse
network.http.spdy.chunk-sizeundefined4096
network.http.spdy.coalesce-hostnamesundefinedtrue
network.http.spdy.enabledundefinedfalse
network.http.spdy.timeoutundefined180
network.http.spdy.use-alternate-protocolundefinedtrue
network.standard-url.encode-query-utf8falseundefined
network.websocket.max-message-size160000002147483647
plugins.click_to_playundefinedfalse
profiler.enabledundefinedfalse
profiler.entriesundefined100000
profiler.intervalundefined10
services.sync.addons.ignoreRepositoryCheckingundefinedfalse
services.sync.addons.ignoreUserEnabledChangesundefinedfalse
services.sync.addons.trustedSourceHostnamesundefinedaddons.mozilla.org
services.sync.engine.addonsundefinedtrue
services.sync.engine.appsundefinedfalse
services.sync.log.logger.engine.addonsundefinedDebug
services.sync.log.logger.engine.appsundefinedDebug
services.sync.prefs.sync.addons.ignoreUserEnabledChangesundefinedtrue
services.sync.prefs.sync.browser.sessionstore.restore_on_demandundefinedtrue
services.sync.registerEnginesBookmarks,Form,History,Password,Prefs,TabBookmarks,Form,History,Password,Prefs,Tab,Addons