It's been rumored to be coming for a while now, but on April 8, Paramount is rolling out the Perry Mason - 50th Anniversary Collection DVD. The set contains 12 episodes (none of which are available on DVD yet, so no double-dipping) as well as a horde of extras.
The episodes are:
"Case of the Wary Wildcatter"
"Case of the Treacherous Toupee"
"Case of the Envious Editor"
"Case of the Barefaced Witness"
"Case of the Counterfeit Crank"
"Case of the Shoplifter's Shoe"
"Case of the Constant Doyle" (Bette Davis fills in for an absent Perry)
"Case of the Deadly Verdict"
"Case of the Bountiful Beauty"
"Case of the Twice-Told Twist" (the color episode)
"Case of the Dead Ringer"
"Case of the Final Fade-Out" (final episode)
There's a ton of bonus features on this set (Paul Brownstein, the DVD producer, always does a good job. He handed Season 1 of The Wild Wild West and Image's releases of The Dick Van Dyke Show, among others). The full list is on TVShowsOnDVD.com, but the ones that jumped out at me were the interviews/intros with Barbara Hale and Perry Mason Returns!
Not sure how this will affect future season releases, but it looks like a great collection.