The NBER, National Bureau of Economic Research, is responsible for timing the start and end of recessions. They say here:
The NBER does not define a recession in terms of two consecutive quarters of decline in real GDP. Rather, a recession is a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production, and wholesale-retail sales.[Emphasis added].
The also say here:
The committee's approach to determining the dates of turning points is retrospective. We wait until sufficient data are available to avoid the need for major revisions. In particular, in determining the date of a peak in activity, and thus the onset of recession, we wait until we are confident that, even in the event that activity begins to rise again immediately, it has declined enough to meet the criterion of depth. As a result, we tend to wait to identify a peak until many months after it actually occurs.[Emphasis added, paragraphs may be re-ordered]
It's more accurate to say that a recession-the way we use the word-is a period of diminishing activity rather than diminished activity. We identify a month when the economy reached a peak of activity and a later month when the economy reached a trough. The time in between is a recession, a period when the economy is contracting.
Most of the recessions identified by our procedures do consist of two or more quarters of declining real GDP, but not all of them. The most recent recession in our chronology was in 2001. According to data as of July 2008, the 2001 recession involved declines in the first and third quarters of 2001 but not in two consecutive quarters. Our procedure differs from the two-quarter rule in a number of ways. First, we consider the depth as well as the duration of the decline in economic activity. Recall that our definition includes the phrase, "a significant decline in economic activity." Second, we use a broader array of indicators than just real GDP. One reason for this is that the GDP data are subject to considerable revision. Third, we use monthly indicators to arrive at a monthly chronology.
Note the part about the revisions: we see here that after revision, 4Q2007 GDP growth was actually NEGATIVE. This happened on or about July 31, 2008. So we still don't know the real 1Q2008 numbers yet, leave alone later quarters.
Mike Shedlock (aka Mish) looks at this issue here. One of his points - "How can we have an understated inflation rate of 4%, and a GDP Price Deflator of just 2.6%?" - is particularly well taken, given the known rigging of the CPI ("hedonic adjustsments" and other such nonsense) described here and shown graphically here. The flaws in GDP statisitics are discussed here.
Summing up: Once youe realize that the "2 quarters of negatice GDP growth" is the mindless repetition by the MSM of an outdated measurement model, you can see that things have been going the wrong way for quite a while.