Tack Sharp is maybe not what you really meant. You can sharpen edges to fool the eye and make it "appear" sharper on the edges. Probably what you meant is getting the highest resolving power to reveal finer details. This is more about the quality of the lens for a particular purpose rather than specifically about cameras. Most modern cameras are capable of resolving fine details. Full frame more so (and also able to reveal the faults of a fine lens).
There are sites that test and review the resolving power of optics. If you are looking for the finest detail then you need to be selective on lens choices and even then compare multiple copies of the same lens as there are differences and some of the differences are striking. Always good to check.
Also there are other factors to consider too. While a lens may test at a high resolving ability, if it suffers from chromatic aberration it's going to be difficult to achieve what you want as eliminating the CA will also eliminate some of the color that reveals the finest detail.
Here is a good site that lets you compare various lenses to see which ones resolve more detail and which ones suffer from CA and how much.http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx
So, a friend and I have been on this quest to shoot a photo like we have seen online countless times or in video training etc. Its where you take a picture of a person and even when you zoom into it at 200% the clarity of the image and sharpness is just off the charts.
We have tried everything to replicate this level of sharpness and just cant. Locked off on tripods, cable release, etc. Its just not working.
Are we expecting too much out of our gear? We are both rocking Canon APS-C (7D, 60D) with good glass 100mm F2, 50 1.4, Zeiss 35mm F2, 25-105 F4. It just feels like we are missing something somewhere because our expectations are to take pictures like scott kelby or joel grimes or someone where the sharpness even zoomed in is amazing without a bunch of post processing.