Eh. You can still get the 3.0.2 firmware from Amazon if you tweak the URL. If you don't trust me altering it then just go to the download page for 3.0.3 and change the URL from 3.0.3 to 3.0.2.
Kindle 3G+WiFi - B00A - 3.0.2
Kindle WiFi - B008 - 3.0.2
Kindle 3G+WiFi - B006 - 3.0.2
Kindle 3G+WiFi - B00A - 3.0.3 (Preview still)
Kindle WiFi - B008 - 3.0.3 (Preview still)
Kindle 3G+WiFi - B006 - 3.0.3 (Preview still)
The preview release so far has always been promoted to release without any changes. This may change in the future if they discover any showstopper bugs.