I recently published my first Android App which is very relevant to this topic of discussion.
Its called "Lock Delay". It modifies the behavior of the Android system lock pattern. Instead of immediately requiring the unlock pattern each and every time the screen shuts off, with Lock Delay, you can set an idle delay of just a few minutes or up to several hours before the lock pattern will be engaged and required to unlock the phone. With this running, there is no need to mess with widgets or manually enabling and disabling the pattern lock.
I think it makes the built in lock pattern mechanism much more usable.
Search for "Lock Delay" on the Android Market. It was developed and tested on a stock Motorola Droid running 2.0.1 but should work with most other android versions 1.5 and up.
Please contact me with any questions, comments or suggestions.