Hi Soar,
yes, I had noticed that, once again, you have returned to the darkside. The lure of DM is very tempting but you must learn to resist.
Still no confirmed date for bulldozer but hopefully some time in June/early July. Gigabyte are already producing motherboards with the AM3+ socket which is a good indicator that the CPU's will be coming along within a couple of months.
Whilst it does appear that certain motherboard manufacturers are offering a BIOS update to enable some existing AM3 socket boards to take the Bulldozer chip, you should bear in mind that they are not telling you the whole picture.
Running one of the new AM3+ processors on an older socket will mean you will lose some of the features of the new chip which, to my mind, defeats the point of getting one in the first place. However, apart from better temperature reporting, it is not clear what, if any, other features will be lost if you use an AM3 socket.
Personally, I wouldn't be spending any money unnecessarily on a new motherboard, at the moment, unless it definitely had an AM3+ socket. It's that period of time when it is really getting too close to the release of the new CPU to rashly spend money but the lack of info is still quite amazing which makes such offers very tempting.