MSI's AM2+ Motherboards Support AM3 Processors
In order to make your board compatible, you simply need to apply a BIOS update. That's it. No new hardware. No soldering. No switching of DIP switches. Just a BIOS update. As you well know, the AM3 processors check in with higher frequencies, fast L3 cache, support for both DDR3 and DDR2 memory, new C1E energy saving functionality and an "advanced architecture also enhances its overclocking prowess."
For a complete look at MSI mainboards and what BIOS is needed in order to support AMD's Phenom II line, point your browser in this direction.