Today I pushed a commit to enable bluetooth in the Eclair rootfs repository. The build service has already assembled an image, so you can grab it and give it a shot. This currently only works for devices with Texas Instruments bluetooth, such as Raphael and Diamond. It does not yet work with Rhodium, which uses a Broadcom chipset.
The commit was a simple few-liner to the Eclair init.rc to add an Android service which handles pairing and connecting to other Bluetooth devices. The Bluetooth chip in the phone was working already (and enabled in Donut), so it was just the Android userspace service which was missing.
As it is now, the bluetooth device appears to inhibit deep sleep for the phone, which in turn causes noticeable power drain. This will be something to take a look at down the road to see if deep sleep can be enabled with bluetooth on. It’s probably a low-priority issue at this point, since bluetooth is not essential, and users who do wish to use it can enable and disable it manually.