Latest firmware for E66 is V410.21.010

Change log

NEW FUNTIONALITIES:
Following baselines/functionalities have been upgraded.
• Nokia Messaging IM2.0.19
• Gimlet v9.6.0.16
• Mail for Exchange 3.0.50

CHANGES AND IMPROVEMENTS:
• Many functionality and Stability improvements in MfE. MFE3.0 has new features like HTML and Subfolders support.
• IM2.0.19 has many localization error corrections. IM installation has been moved to Phone Memory instead of Memory Card. IM response time has improved (Ex: entry/exit/edit/save options)
• Phone activation baseline upgraded
GENERAL
• Stability and functionality improvements
• Email and WLAN functionality improvements
• Email application freezes
• Samsung memory reboot issues
CALL HANDLING
• Fix for phone reboot issue when contact has Internet telephony detail
CALENDAR/CLOCK
• Fix for Chinese characters in Lunar calendar
• Fix for Western Sahara country legal issue
CONNECTIVITY
• Improvement in Connection establishment with slow gprs
• Fix for WLANsniffer scanning enabled in the background when it should be disabled
CONTACTS/PHONEBOOK
• Fix for contact search with space
EMAIL
• Mail for Exchange upgraded from 2.9.176 to 3.0.50
• Gimlet updated to v9.6.0.16
• Many functionality and stability improvements in MfE
• Fix for Gmail folder issue in UK and Germany for Gmail/GoogleMail configuration
• Fix for email application freeze
QWERTY KEYBOARD
• Usability improvements
• Fix for Backslash character for Portugese language
• Fix for missing characters in French/Italian languages
MESSAGING
• Improvement in sending SMS when memory is full
• Nokia IM chat response time improved. Lot of localization errors fixed

It depends where you install the application. If you installed in memory card, then should be find, if not, just back up all your data using Nokia pc suite

i dun think so. bcos i update my phone's FW b4, and the app stilll there. if u woory abt it, can try to back up 1st.