Froyo introduces a technology called JIT compiler or Just In Time compiler. Android apps/system uses a highly customized version of java and like any version of java, its an interpreted language, in that as each instruction is processed, its compiled into machine code. JIT does this at once for an app at execution time instead of doing it during the execution, thus increasing the performance on an order of magnitude.
Froyo, also enhances its exchange support to play better with enterprise emails, they've also tweaked the home page, and other areas.
moto, I'm sure will add their spin on it, and touch up moto blur a bit to make it even better on 2.2 then 2.1