I'm still on OS2007, and switchonbt works for me - I haven't tried an OS2008 version, obviously. It's unfortunate if it doesn't work, it fixes a big deficiency in the Nokia BT handling.

BTW, I can't say I have noticed much battery usage with BT on. I used to keep BT on at all times in the beginning, I only started to turn it off (to actually make some good use of the broken design) when my status bar became full (another broken design, that status bar.. it can't be stretched even though there's lots of space).