IPv6 is proposed as an almost unlimited source of addresses to overcome the IPv4 address shortage some people have suggested. As IPv6 addresses are 128-bit long, 2^128 (aprox 3.4 x 10^38 ) addresses are possible. This should be large enough.
To put things into perspective consider the following problem: How many IPv6 addresses could you put into each squared centimeter of the planet? (Assume the Earth is a regular sphere of 40.000 Km of perimeter).
And a second part … compare the above number of IPv6 addresses per square centimeter to the total address space of IPv4.