You're actually asking about their resolving power, not resolution. Wikipedia and Cambridge in Colour both offer good entry level explanations of these subjects.
Also check out DPreview's test results - the ISO12233 resolving power test charts. This will let you compare all three cameras.
But in the end - there's much more to any camera than it's resolving power capabilities so my advice would be not to overestimate it.
|Bianca Buitendag-7809 by vbuhay|
|Sunrise in Paradise by OB Foto|
from Booby Prize
|The Battle for the Lead by Photo Pete|
from Bicycle sports
|Cecelia's Eyes by Madeleine Hart|
from - Jenny from the Block - (Colors that pop + A white Border)