[Note: I'm still surfing the international highway; what follows is a pre-scheduled post.]
So I celebrated the other night as three 2007-08 Islanders -- including one who was captain as late as March 2009 -- won the Cup as members of the Pittsburgh Penguins. Futility jokes aside, how rare is it to leave the Islanders and become a Stanley Cup champion within the next year? Very.
John Tonelli got to the finals with Calgary in 1986, but he was gone to L.A. by the time the Flames returned to finish the job in 1989.
Tomas Jonsson went to Edmonton for their playoff push in 1988-89, but their Smythe Division rivals captured the Cup that year, and the following season -- when the Oilers grabbed their fifth and final Cup -- Jonsson was back in Sweden.
Brent Sutter and Brad Lauer went to Chicago early in the 1991-92 season (swapped for Steve Thomas and Adam Creighton), but they, too, fell short in the finals that year under Mike Keenan.
Bill Berg was shipped to Toronto mid-way through 1992-93. What's that matter, you ask? Well Leafs partisans will tell you all that separated the Leafs from a Cup that year was Kerry Fraser.
Uwe Krupp went to Quebec in the summer of 1994, but the franchise didn't win the Cup (with Krupp scoring the game-winner) until two seasons later, after they'd become the Avalanche. Speaking of the 1996 champions, technically Claude Lemieux was an Islander property on the eve of that season -- but only on paper as part of the three-way deal involving Wendel Clark and Steve Thomas. Later that summer, Brent Severyn was sent to Colorado, but it was too late for a Cup.
In the spring of 1999, the Islanders traded Sergei Nemchinov -- one of the rare players to dress for all three metro teams -- to the Devils, where he won the Stanley Cup (for the second time, after 1994) the next season.
After the lockout, Michael Peca went to Edmonton in exchange for Mike York in 2005, and that following season Peca's Oilers made it all the way to the finals only to loose to Carolina.
So that's from a skim through Zandberg's invaluable NHL Trade History site. There's likely some I missed, particularly in the free agent arena -- although none come to mind. Let me know if you can think of any others, but by my count, when it comes to playing for the Islanders one season and winning the Cup elsewhere the next, there's just a bunch of close calls, plus Nemchinov and the trio of Penguins who hoisted the Cup just last week.