JSON can be a little hard to read because it's generally meant to be served without characters such as spaces and newlines that would make it human-readable.

Here's output from the fast ticker:

{
  "result":"success",
  "data":{
    "last_local":{
      "value":"136.87303",
      "value_int":"13687303",
      "display":"$136.87",
      "display_short":"$136.87",
      "currency":"USD"
    },
    "last":{
      "value":"136.87303",
      "value_int":"13687303",
      "display":"$136.87",
      "display_short":"$136.87",
      "currency":"USD"
    },
    "last_orig":{
      "value":"136.87303",
      "value_int":"13687303",
      "display":"$136.87",
      "display_short":"$136.87",
      "currency":"USD"
    },
    "last_all":{
      "value":"136.87303",
      "value_int":"13687303",
      "display":"$136.87",
      "display_short":"$136.87",
      "currency":"USD"
    },
    "buy":{
      "value":"136.10500",
      "value_int":"13610500",
      "display":"$136.11",
      "display_short":"$136.11",
      "currency":"USD"
    },
    "sell":{
      "value":"136.87250",
      "value_int":"13687250",
      "display":"$136.87",
      "display_short":"$136.87",
      "currency":"USD"
    },
    "now":"1381085718504609"
  }
}

The "result" item is always guaranteed to be there, but has of course varying content based on whether or not the call was successful. The "data" element contains a series of prices, with each name indicating its price.

Most JSON parsers in interpreted languages such as Ruby, PHP, and Python parse JSON into a hash or dictionary. You'd want the value of the "value" key of the "last" key of the "data" key.

Here's a one-liner version in Ruby for the v2 ticker:

ruby -e '%w(open-uri json).each{|b| require b}; open("http://data.mtgox.com/api/2/BTCUSD/money/ticker_fast") {|d| puts JSON.parse(d.read)["data"]["last"]["value"]}'

Or something a little more readable:

require "open-uri" 
require "json"

open("http://data.mtgox.com/api/2/BTCUSD/money/ticker_fast") do |d| 
  json = JSON.parse(d.read)
  puts json["data"]["last"]["value"]
end

Here's a one-liner version in Ruby for the old ticker:

ruby -e '%w(open-uri json).each{|b| require b}; open("https://mtgox.com/api/1/BTCUSD/ticker") {|d| puts JSON.parse(d.read)["return"]["last"]["value"]}'

Or something a little more readable:

require "open-uri" 
require "json"

open("https://mtgox.com/api/1/BTCUSD/ticker") do |d| 
  json = JSON.parse(d.read)
  puts json["return"]["last"]["value"]
end

Ok this should answer your question,

import urllib2, json

x = float(json.loads(urllib2.urlopen('https://mtgox.com/api/1/BTCUSD/ticker').read())['return']['last']['value'])

print x

This returns the last value for the MTGox USD price for bitcoins