Zappletoo from xda got this working on the doughnut. I tried it and it seems to work for the droid on 3g too. It is one app for Yahoo, AIM, and windows live messenger.
1. adb shell
2. mount -o remount,rw /dev/mtd/mtdblock4 /system
3. adb push ImProvider.zip /system/app/ImProvider.apk
4. adb push IM.zip /system/app/IM.apk