jimbeetle - 3:29 pm on May 8, 2008 (gmt 0) <added>
I am not sure if Google sends emails to anyone about their websites -- that would be awesome customer service from any company. This email is probably a fake.
Google has been making an effort over the past year or two to notify webmasters when it finds problems. It isn't at the "awesome customer service" point yet but has been slowly and steadily expanding.
workingNOMAD, besides removing those hidden links did you apply any available security patches for the blog software you use? This might be an important point for reinclusion if applicable.