Of the various definitions of liberalism noted by Lacy in this post, Obama falls into the 'liberal' classification in most of them. But it is the 'temperment and style' criteria that Lacy rightfully notes several commentators have seized on to say that Obama is, at his core, a conservative, and it is with this defintion that I think bugs me so much (not in the way Lacy defined it, but rather in the way that MSM commentators use it). To say that Obama is even-headed, thoughtful, and pragmatic, ergo he is conservative, both ignores a lot of wild-eyed nutters who self-identify as conservative of late and suggests that all liberals are, by contrast, irrational, emotional, and impulsive. Now, it is possible that these commentators are using the French Revolution era distinction of liberal and conservative, but I kinda doubt that.
I think that a good chunk of the commentators who suggest that Obama is, by any definition, conservative are pretty much fooling themselves for the sake of comfort. They just know they're not liberals, because the word sends chills up their spine, yet they also see the GOP and realize that's not what they are either, and perhaps they even see something refreshing in Obama -- thus, if they like Obama, he must be a conservative.