Yes. Two ways, in fact. If you enter the lyrics of a song and space them out with the chords above the lyrics, WP will allow you to easily transpose those chords from one key to another.
Also, if you have uploaded an MP3 of the song, WP allows you generate a transposed version of the MP3, where it actually shifts the pitch up or down, by key or half-steps. To learn more, see the Key Transposing - MP3 article.