Managed mode Layer 2 Bridging - Solution?

[paravoid]

Hello list,
I've read and understand why a layer 2 bridge can't work with a hostap in
managed mode.
I've seen though layer 2 bridging working in the following situations:
a) Linksys WRT54G's proprietary binary module + binary utility (only after
"wl wet on")
b) Cisco's Aironet driver (Windows only)
c) External Client Bridges (D-Link DWL-810+, DWL-900+)

As far as I can understand, those devices when participating on a bridge and
working in managed mode, associate on the AP all the MACs coming from the
other side of the bridge. So in the Associated stations in the AP menu you
can see all the MACs of the ethernet devices behind the bridge.

Is this possible by writing code on the driver side or this feature needs
additional code on the firmware? If it is, are there any plans developing
this?

Thanks in advance ;-)