From the Union of Concerned Scientists:
Global average surface temperatures pushed 2005 into a virtual tie with 1998 as the hottest year on record. For people living in the Northern HemisphereÂmost of the world's populationÂ2005 was the hottest year on record since 1880, the earliest year for which reliable instrumental records were available worldwide.
And here's what the footnote means:
 The years 1998 and 2005 are so similar (i.e., within the error range of the different analysis methods or a few hundredths of a degree Celsius) that independent groups (e.g., NOAA, NASA, and the United Kingdom Meteorological Office) calculating these rankings based on reports from the same data-collecting stations around the world disagree on which year should be ranked first. Annual global rankings are based on combined land-air surface temperature and sea surface temperature since 1880.
Although this is shitty news for the planet, it should help put to bed the argument floating around in anti-Kyoto/Conservative circles that Global Warming stopped in 1998. This claim was based on the fact that 1998 was the hottest year on record (helped by a strong El Nino); therefore, the argument runs, the world has been cooling since that time. More to the point is the fact that 19 of the 20 hottest years on record have occurred since 1980.