1150 came with my phone. I have been using a program that will dim the screen for less than a week and I'm not sure yet what I think of it and/or if it's made my phone a wee bit less stable than prior.
What's involved is using a program called Tornado PowerControl. It allows you to underclock your device or overclock it. Underclocking saves battery power and overclocking uses more but also makes the phone operate quicker. It's an easy interface and does most everything by itself or you can get under the hood and tinker.
You can set it to run when you start the phone and have the screen dim by defualt. It's very easy to do these things manually as well.
Check it out here:http://surrealnetworks.com/mpx/SDAapps.htm
It's called "PowerControl+OMAP"
This would involve downloading the CAB file and moving that onto your phone. Then you'd need to "install" it from there. Hopefully you're familiar with this process.
Lastly, if it doesn't work right and your phone takes a dive (upon trying any new program...not just this one) you could end up having to do a hard reset. That would mean you'd lose everything you've added to your phone and it'll be just like new again. So, if you've done a lot of customizing, you might want to look into Sprite backup software available here:http://www.spritesoftware.com/
Sprite is a VERY worthwhile investment if you're going to start "playing" with your phone and trying out new things. They don't always work right and you're gonna wish you could turn back time. Sprite allows you to do just that. I highly recommend it.
PowerControl+OMAP installed just fine on mine and I've been using it a few days now. It definetly will dim your screen for you and save battery consumption at the same time.
There might be other programs (or, a reg edit) that'll do the same, this is just one I'm aware of.
Lastly, go into the settings\power management menu and check that your backlight timeout and display timesout settings are configured the way you want.
Devices: T-Mobile MDA (Cingular SIM), i-mate SP5m (sitting in a drawer at the moment while I attempt to migrate to PPC permanently), Cingular 3125 (unlocked and in use on T-Mobile), Motorola MPx220 (retired), Motorola MPx200 (retired)
Accessories: Plantronics Explorer 330 & 2G Patriot Micro-SD (use w/MDA), Kingston 2G mini-SD used in SP5m, Plantronics Discovery 640 & 2G San Disk micro-SD (use w/3125), Jabra A210 BT adapter + Motorola HS805 (retired)