Hello,
From what I've read it appears that *Some* current AM3 boards are capable of running AM3+ CPUs with the current 8** series chipset, however this is something which the motherboard manufactures are supporting and not AMD (Like Core Unlocking I guess!). My understanding however is that the explanation of why only some mostly the more high end motherboard can be upgraded to support he new AM3 + CPUs is that they place a higher demand on the electrical components of the motherboard.
It is however possible that there might be performance disadvantages when using current boards but I'm only guessing as I have no idea on the specification of the new boards or CPUs. There are also meant to be a pin change (Extra one added) so its possible support might not be full for all new AM3+ CPUs (Maybe it will not support the CPUs with embedded GPU or something like that?). It's also possible that they might not be compatible with other future AM3+ CPUs.
So what do we know so far?
Gigabyte:
Have listed a new range of products, all of which have a "Black" CPU socket and are listed as AM3+ on their website, all motherboards are listed a Rev 3.1. These motherboard are meant to have a native am3b (AM3+) socket with the correct amount of pins, I would therefore presume they should have good future proof support. As far as I'm aware no support for any existing products or revisions pre 3.1 have been released.
http://www.gigabyte.com/products/list.aspx?s=42&jid=10&p=2&v=26
These should be filtering there way down to the likes of OCUK although I have no idea if they have this rev of boards in stock yet, I can't say I've noticed anything on there website as yet saying so anyway.
Asus:
Have anounced that some of there motherboard including their flagship and popular Crosshair IV Formula are upgradable with a simple bios (Currently only Beta) upgrade.
Full details can be found here, they also list a large amount of soon to be released products which will be compatible based on current chips but labled M5 models:
http://event.asus.com/2011/mb/AM3_PLUS_Ready/
A lot of which already available from OCUK!
MSI:
Have also announced support on a few of there current models with more bios upgrades to follow with support.
Details can be found here:
http://event.msi.com/mb/am3+/
AsRock:
They are also releasing some new boards with AM3+ support most of which are R2.0 apart from the 890FX Deluxe5:
http://www.asrock.com/mb/overview.asp?Model=890FX%20Deluxe5
http://www.asrock.com/mb/overview.asp?Model=890GX%20Extreme4%20R2.0
http://www.asrock.com/mb/overview.asp?Model=890GM%20Pro3%20R2.0
http://www.asrock.com/mb/overview.asp?Model=870%20Extreme3%20R2.0
I hope you find this useful
Michael