To give you a more serious answer:
First, Angry Birds cost a lot less to make than NSMB Wii. With the manpower/capital needed to make that game, Rovio could make several Angry Birds type games.
Second, the threat to gaming from these types of mobile games is mostly toward the kinds of games Nintendo made popular with the Wii- Wii Sports, Wii Fit, etc. Actually, Nintendo probably created this industry with their success with the Wii- and now it's beginning to be turned against them.
Third, the threat is much bigger in the minds of Wall Street people than it actually is in reality. Remember Apple is the latest big thing in the stock market, that has gone up and up and up, and is now the biggest company by market cap in the world. Meanwhile Sony and Nintendo are losing money, in large part because we're at the end of a cycle and they need new systems to be released. Wall Street will see Apple (and any associated companies) as a bigger threat to gaming companies than it is. Facebook is big too- and at least until Wall Street can actually buy FB stock, it's sort of using related companies as a proxy. Does anyone really believe Zynga is worth $8 billion dollars? I doubt very many do, but it's the next best thing to Facebook if you want to buy FB stock for another month.
--
Congratulations to SuperNiceDog, Guru Winner, who was smart enough to pick
your 7 time champion, Link.