I have Powershot A450 [CCD sensor] that seems does not have any shutter assembly.And it can capture up to 1/2000 sec.
Mobile cameras also do not have any physical shutter mechanism.

Why shutter assembly is necessary for a DSLR?

If that dslr can do without any physical shutter assembly it can definitely reduce cost, camera shake etc. etc.

techno geeks, please enlighten me