The quick answer to this question is a resounding no. Loads of fans speculated that they could see "shaving bumps" on Sajak's head, or that there was no way the bald head was fake because they didn't see any lines or other tell-tale signs.
In reality, Sajak is not bald and that's his real hair that he's sporting on the show. The big April 1st reveal was just a joke, though rumors and speculation persist to this day. You can see the clip from the end of that show on YouTube.
Oddly enough, Sajak's hair has now earned the same kind of fan obsession as Alex Trebek's moustache.