I learned about this in class the other day, and the poem reads to my ears like typical British dry wit. On the other hand, there appears to be some cross-use by both detractors and supporters of American imperialism at the time it was penned.
This is evident in the sourced Wikipedia article on the topic. Is there any evidence beyond the Wiki as to whether Kipling had a particular intent behind the poem?
Shadowing the White Man's Burden contains some discussion of the conflicting opinions of both the educated and the uneducated at the time. You could make a convincing argument either way on the subject. I've always been of the mind that Kipling merely sought to foment discussion rather than suggest a destiny or course of action (though I may be giving Kipling's intelligence too much credit).
Additional info: The Kipling Society provides a nice combination of the poem and a personal letter from the same timeframe to promote the idea that Kipling saw the "White Man's Burden" as a sincere "humanitarian" mission to bring the savages out of depravity.