Here's a pdf report from a warranty company. They analyzed the failure rate of 60,000 digital cameras within the first 3 years of ownership and came up with some interesting findings.
Most reliable digital cameras for less than $300
Most reliable digital cameras between $300-$500
They didn't have enough data to rank DSLRs but they did say that there was "no significant difference between Nikon and canon's reliability".
Panasonic is doing very well with their EVIL camera's and now they seem to a very reliable brand too. So it looks like Nikon and canon should be worrying about Panasonic over taking their sales in 5 years and not Sony!