Relocation of teams is a hot topic in the NHL, NBA and NFL. Here is a list from Wikipedia of professional sports teams that have relocated.
The most recent league to have a team move is the NBA, with the Seattle SuperSonics becoming the Oklahoma City Thunder in 2008. MLB is second as far as most recent moves, with the Expos moving to Washington in 2005. Both the NFL and NHL haven't had a team move since 1997. The Houston Oilers moved to Memphis and became the Tennessee Oilers, while the Hartford Whalers became the Carolina Hurricanes.
Before the Expos headed to Washington, the last time a team moved in baseball was in 1972 when Washington lost its team to Texas.
While the NHL hasn't had a team move since 1997, between 1993 and 1997, 4 teams relocated (Stars, Nordiques, Whalers and Jets).
Gary Bettman became Commissioner on February 1, 1993.
When Bettman started as Commissioner, the NHL had already expanded by 3 teams to 24 starting with the 1991-92 season, and two more were set to be announced by the expansion committee: the Florida Panthers and Mighty Ducks of Anaheim, who would begin play in 1993–94. Similar to the previous expansion cycles, the focus was on placing teams in the southern United States. The Nashville Predators (1998), Atlanta Thrashers (1999), Minnesota Wild (2000) and Columbus Blue Jackets (2000) completed the NHL's expansion period, bringing the league to 30 teams.