andreadbc

I'm listing the differences here so that it's easier to keep things straight... and also taking the oportunity to predict sudden FTer mass migration to Ecuador Colombia.

Premium

Colombia

1. 28.000 km
2. 25 LAN / TAM segments

Ecuador

1. 35.000 km
2. 36 LAN / TAM segments

Everyone else
(Argentina, Chile, Perú, Germany, France, Canada, Brazil, US, Uruguay, Mexico, Spain, UK, Australia, NZ, others)

1. 40.000 km
2. 30 LAN / TAM segments

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Premium Silver

Colombia

1. 55.000 km
2. 35 LAN / TAM segments
3. 30.000 km + 2 medium or long haul segments on LAN / TAM Business

Ecuador

1. 60.000 km
2. 72 LAN / TAM segments
3. 30.000 km + 2 medium or long haul segments on LAN / TAM Business

Perú

1. 65.000 km (minimum 32.500 km on LAN / TAM)
2. 55 LAN / TAM segments
3. 40.000 km + 8 medium or long haul segments on LAN / TAM Business

Argentina, Uruguay, Spain, France (sites still showing 2012 rules)

1. 80.000 km
2. 60 LAN / TAM segments
3. 40.000 km + 4 medium or long haul segments on LAN / TAM Business

Everyone Else
Chile, Brazil, Canada, Germany, México, US, UK, Australia, New Zealand, others

1. 80.000 km (minimum 40.000 km on LAN / TAM)
2. 60 LAN / TAM segments
3. 40.000 km + 6 medium or long haul segments on LAN / TAM Business

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Comodoro

Colombia

1. 100.000 km
2. 70 LAN / TAM segments
3. 50.000 km + 4 segments on LAN / TAM Business

Ecuador

1. 100.000 km
2. 120 LAN / TAM segments
3. 50.000 km + 4 medium or long haul segments on LAN / TAM Business

Perú

1. 130.000 km (minimum 65.000 km on LAN / TAM)
2. 85 LAN/TAM segments
3. 80.000 km + 10 medium or long haul segments on LAN or TAM Business

Argentina, Uruguay, Spain, France (sites still showing 2012 rules)

1. 150.000 km
2. 100 LAN / TAM segments
3. 90.000 km + 6 medium or long haul segments on LAN / TAM Business

Everyone else
(Chile, Brazil, Australia, Canada, México, Germany, USA, UK, New Zealand, others)

1. 150.000 km (minimum 75.000 km on LAN / TAM)
2. 100 LAN / TAM segments
3. 80.000 km + 8 medium or long haul segments on LAN / TAM Business

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Comodoro Black

Everyone

1. 210.000 km on LAN / TAM
2. 180.000 km + 16 medium or long haul segments on LAN/TAM Business

Kilometers can be on LAN or oneworld flights in a calendar year. This also includes LAN Premium Business km bonuses, TAM Business and First bonuses and LAN or TAM high-fare km bonuses. From 2013 onwards, flights sold by LAN, with a LAN code and operated by TAM also earn qualifying kms.
In all cases there's a 4 segments on LAN / TAM requirement.
Medium or long haul flights are "international flights with a distance of more than 1600 km between stops". There's a list here, but it's missing some flights that fit the description.

Updated with recent changes, some country-sites (Argentina, Uruguay, France, Spain) haven't been updated so far (FEB 2013)