I disagree with Spehro -- the right image is much better, ie less resonant. The circuit on the left will see "antiresonance" -- At a certain frequency in the 100MHz range, the 10uF cap will start to look like an inductor, while the .1uF capacitor will still look like a capacitor, making the pair of them behave like an LC tank circuit. Around that frequency, this tank circuit will not sink or source any current, but rather just swish it back and forth like so much mouthwash, and so the two caps together will have very high impedance, making them lousy for decoupling.

As a very broad rule of thumb, it is a bad idea to have two ceramic caps on the same rail that are widely different in capacitance, without some other in-between values on there too. (For example, you can put a .1uF, and .68uF, 2.2uF, and 10uF all on the same rail, but if you just have .1uF and 10uF you might have problems.)

The figure on the right has a ferrite between the mismatched capacitors, dampening the LC tank circuit with a resistance (because ferrites are resistive above 100MHz, not inductive) and this prevents the caps from interfering with each other.

Another solution would be to use a tantalum or electrolytic cap for the 10uF, because its built-in ESR resistance would dampen the tank circuit too (but such a cap would be useless for filtering high frequency noise).

I am getting all of this from a really useful application note by Murata: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.murata.com%2F~%2Fmedia%2Fwebrenewal%2Fsupport%2Flibrary%2Fcatalog%2Fproducts%2Femc%2Femifil%2Fc39e.ashx&ei=KPdLVanDAoGANtLbgcAC&usg=AFQjCNFchvGkn3i18z9bF8pXtpmg6y_pTg&sig2=yFpsftRLDZ-ySU9AhYq8tQ

Lots of nifty combinations of ferrites, inductors and caps used for decoupling can be found there.

I disagree with Spehro -- the right image is much better, ie less resonant. The circuit on the left will see "antiresonance" -- At a certain frequency in the 100MHz range, the 10uF cap will start to look like an inductor, while the .1uF capacitor will still look like a capacitor, making the pair of them behave like an LC tank circuit. Around that frequency, this tank circuit will not sink or source any current, but rather just swish it back and forth like so much mouthwash, and so the two caps together will have very high impedance, making them lousy for decoupling.

As a very broad rule of thumb, it is a bad idea to have two ceramic caps on the same rail that are widely different in capacitance, without some other in-between values on there too. (For example, you can put a .1uF, and .68uF, 2.2uF, and 10uF all on the same rail, but if you just have .1uF and 10uF you might have problems.)

The figure on the right has a ferrite between the mismatched capacitors, dampening the LC tank circuit with a resistance (because ferrites are resistive above 100MHz, not inductive) and this prevents the caps from interfering with each other.

Another solution would be to use a tantalum or electrolytic cap for the 10uF, because its built-in ESR resistance would dampen the tank circuit too (but such a cap would be useless for filtering high frequency noise).

I am getting all of this from a really useful application note by Murata.

Lots of nifty combinations of ferrites, inductors and caps used for decoupling can be found there.