The flu shot and the H1N1 shot are different shots. H1N1 is actually the same strain as the Spanish Influenza. In reality, it's no different than any other flu except that it attacks the young and healthy, not infants and elderly, and that it weakens your immunities, but more on that in a sec.
Depending on how you take the vaccine, it will effect how contagious you are. Intravenously, it's a dead, inactive strain. If you take the nasal spray you're receiving a live strain. Although it will be harmless to you, you will be contagious for a few days afterwards, so please be aware of what you're going to be doing in those days. People won't be dropping in your wake, but you have to be careful of where you're sneezing, whose hand you are shaking and how often you're washing your hands.
What's underlying the H1N1 concerns isn't that if you get it, there's no coming back. The CDC is looking ahead to the next pandemic, and that's the Avian flu. That never went away and even though the hysteria around it has cooled, it's still a countdown until that becomes a pandemic. Why it's relevant is because if you've had H1N1, you're twice as likely to contract the Avian version, for which there is no cure. The more people who are vaccinated against H1N1, the more people won't have the wrecked immunities that will make the Avian flu worse than it could be.
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