According to Yahoo News This is why 9-9-2009 is so special to numerologists and also in Chinese Culture:

As part of his obsession with numbers both mathematically and divine, and like many mathematicians before and since, Pythagoras noted that nine in particular had many unique properties.

Any grade-schooler could tell you, for example, that the sum of the two-digits resulting from nine multiplied by any other single-digit number will equal nine. So 9×3=27, and 2+7=9.

Multiply nine by any two, three or four-digit number and the sums of those will also break down to nine. For example: 9×62 = 558; 5+5+8=18; 1+8=9.

Sept. 9 also happens to be the 252nd day of the year (2 + 5 +2)…

The article then goes on to say:

The Chinese pulled out all the stops to celebrate their lucky number eight during last year’s Summer Olympics, ringing the games in at 8 p.m. on 08/08/08. What many might not realize is that nine comes in second on their list of auspicious digits and is associated with long life, due to how similar its pronunciation is to the local word for long-lasting (eight sounds like wealth).

Historically, ancient Chinese emperors associated themselves closely with the number nine, which appeared prominently in architecture and royal dress, often in the form of nine fearsome dragons. The imperial dynasties were so convinced of the power of the number nine that the palace complex at Beijing’s Forbidden City is rumored to have been built with 9,999 rooms.

So, I guess what makes my day special is that I not only managed to get one photograph – of my computer screen at 9/9/9 9:09:09 – but one of my desk clock as well:

And.. since the next set of repeating dates will not be until next year (10/10/10 at 10:10) – it just makes it that much more fun.
How cool is that?