Before the big reveal, here's the headless photo from Name That Bump 4:
AHA! You guys are getting a hang of this. Everyone guessed correctly. Nicely done. The lovely lady with the lovely baby bump is Alyson Hannigan, who stars in How I Met Your Mother and has two daughters, Satyana (born in 2009) and Keeva (born earlier this year). Alyson is pregnant with Satyana in this photo.