Why does 1 == True but 2 != True in Python?

Because Boolean in Python is a subtype of integers. From the documentation:

Boolean values are the two constant objects False and True. They are used to represent truth values (although other values can also be considered false or true). In numeric contexts (for example when used as the argument to an arithmetic operator), they behave like the integers 0 and 1, respectively. The built-in function bool() can be used to cast any value to a Boolean, if the value can be interpreted as a truth value (see section Truth Value Testing above).

http://docs.python.org/library/stdtypes.html#boolean-values

Because instances of bool are also instances of int in python. True happens to be equals to integer 1.

Take a look at this example:

[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin
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>>> isinstance(True, int)
True
>>> int(True)
1
>>> 

It's standard binary conventions: 1 is true, 0 is false.

It's like 1 means "on" in machine language, and 0 means "off".

Because of this the bool type is just a subtype of int in Python, with 1 == True and 0 == False.

However any non-zero numeric value will be evaluated as True in a conditional statement:

>>> if 2: print "ok"
ok
>>> 2 == True
False

Equality testing is different than boolean testing:

>>> bool(1)
True
>>> bool(2)
True
>>> bool(-1)
True
>>> bool(0)
False