I am looking at adopting a skeletal animation format (as prompted here) for an RTS game. The individual representation of each model on-screen will be small but there will be lots of them!

In skeletal animation e.g. MD5 files, each individual vertex can be attached to an arbitrary number of joints.

How can you efficiently support this whilst doing the interpolation in GLSL? Or do engines do their animation on the CPU?

Or do engines set arbitrary limits on maximum joints per vertex and invoke nop multiplies for those joints that don't use the maximum number?

Are there games that use skeletal animation in an RTS-like setting thus proving that on integrated graphics cards I have nothing to worry about in going the bones route?