Ok, so there’s three known problems that are reported with BC 2.2.8, just that you know:
 There can be black screens with a couple of mods integrating the API, such as Railcraft. This is really my bad, I’ve updated the API without thinking of the potential incompatiblities here. The workaround is to install 2.2.7 instead from http://www.mod-buildcraft.com/download/previous-releases/.
 The quarry doesn’t mine grass. This is a minor issue, but if it’s getting into your nerves, installing 2.2.7 works too.
 Grass doesn’t drop seeds. This is a Forge issue, I want to make some verification before releasing Forge 1.2.2 with the fix. Out soon!
* Edit * Go check out Forge 1.2.2 on http://sourceforge.net/projects/minecraftforge/files/1.2.2/