After updating the iPhone, I then quickpwn'd to 2.2.1 (with "add cydia" and "add installer" selected, and now do not have cydia and installer.
The odd thing is that I still have my blank icon on my screen from 2.1 and all my old mail/contacts are still available without syncing back after jailbreak.
Did you happen to have Cydia and Installer icons hidden or in a Categories folder before you upgraded? If you did you need to Install SBSettings and under "more" you can unhide the icons.
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iPhone, the Swiss Army knife of the 21st Century.
1st go to settings/general/restrictions/off
If it does not help,then
If you have Cydia, install Quickgold and Poof to unhide the icons
Install SBSettings&unhide any apps that are hidden
Launch the Settings app&disable/reenable restrictions.Doing this should unhide all the hidden apps
If Cydia is hidden,you can use Apt-get&install Quickgold from the SSH prompt
Worst case scenario,if nothing works,you can use iPhoneBrowser or whatever&delete the files located at/var/mobile/Library/Preferences/com.apple.SpringBoard.plist&the reboot your phone...