This article in the Washington Post ("After Va.'s Losses In Court, a Flurry Of Finger-Pointing," by Jerry Markon, Saturday, September 20, 2008; Page B01) suggests that a string of successful constitutional challenges to recent Virginia statutes could be either a coincidence or the result of "the General Assembly's willingness to pass aggressive measures that are more likely to face a constitutional challenge."
It's hard to generalize from the three cited cases. On the spam statute, the majority of the Supreme Court was for it before they were against it. On the partial birth abortion statute, the Fourth Circuit has granted rehearing. The transportation funding case is the one that makes you scratch your head and wonder how they thought that would ever work.