We’ve seen two tweets from @BarackObama in the last 12 hours.

That follows one tweet yesterday and two tweets last week. Obama tweeted seven times in May, twice in April, once in March, not at all in February and twice in January.

Before that, the last time Obama tweeted was November fifth.

The last time Obama tweeted twice in one day? Election day.

First quarter ad sales were off 5% versus Q1 ’08, the IAB estimates. This is the first year-over-year decline in quarterly Internet advertising since 2002.

Versus the holiday-bloated Q4, the Q1 number was an even more horrendous decline, down 17%.

Relative to the rest of the economy, the Internet advertising decline doesn’t look outrageous. But the rest of the economy isn’t still pumping out product — more cars, more hotdogs, more washingmachines, more homes — with reckless abandon. Producers have cut back to reduce costs and avoid stockpiling goods nobody will buy.

The same isn’t true online. New dotcoms are still being conceived and birthed daily, and CGM (postings on Youtube, Myspace, Flickr etc) is still doubling yearly.

Malthusian pricing Armageddon impends.

Update: Here’s more data on overall advertising trends. The Internet’s Q1 decline looks wonderful relative to things like ad spends in local Sunday supplements (-38%) and B2B magazines (-30%) and spot TV 101-210DMAs (29%.)

David Carr wanders around a dotcom party in NYC:

I wandered the rest of the party and noticed people staring at me. Had I become the dad in the basement at the teenage party? No, as it turned out, it was the analog act of taking notes with a pen on a notebook that was freaking people out. I may as well have been prancing around with an abacus.

BTW, I just finished Carr’s brilliant and terrifying “Night of the gun.” Adjectives don’t do it justice, so I’ll just say my heart pounded and ached throughout.

Comparing the demographics of PerezHilton’s Twitter followers with those of his blog’s readers, we found Perez’s tweeps to be significantly younger than the blog’s readers. Also more female, Libertarian and comment-prone. Interesting eh?

We’d love to run more comparisons like this, so let us know if you’d like to run a parallel blog/twitter demographic survey.