If you can't reconnect to your WiFi until you reboot your Froyo device, Wifix (lite) will probably help you. Just click the "Reassign" button, and about 8 seconds later you will be reconnected to your WiFi. You can use "Reconnect" if it doesn't work for you. There is also a "Keep Connection" checkbox that prevents your WiFi connection from been deactivated.
Initial freecode announcement.