Android 2.3.3 (Gingerbread) is available for Samsung Galaxy Tab now.
In order to perform the update using the "official" way, you need a computer installed with latest version of Samsung Kies.
Launch the Kies application in the computer, then connect your Samsung Galaxy Tab to it with the USB cable. Set the connection type to be "Samsung Kies".
Kies will detect the Samsung Galaxy Tab and automatically inform you the availability of Gingerbread update.
The process starts with downloading the update file to your computer.
After that, you are given a chance to backup your data in the phone to Kies. Although this update will not cause any data or setting lost to your Samsung Galaxy Tab, it is always a wise choice to perform a backup, just in case.
Then, your Samsung Galaxy Tab will be automatically rebooted into download mode, and the update file will be transferred from your computer to the Tab.
Once the transfer is completed, the update process will begin. Then, your Tab will be rebooted again. It will take some time during its first boot up after the update.
You will be advised by Kies to disconnect the USB cable, reboot the Tab again, then connect back the USB cable. Your computer will then update its USB driver to connect to your Tab with the new Android Gingerbread ROM.
Among the new things after this update are 2 new apps installed in your Tab, namely Sketch Memo and Pulse. Sketch Memo is a pretty handy app that worth a try, but it doesn't come with any widget, which I think it should.