Bukkit

2.5.2

• Additions
  • Added suggestion for misspelled arenas
• Improvements
  • Continued to work on messages/color scheme
• Bug Fixes
  • Fixed error with CTFFlag
  • Fixed conflict with Multiverse

2.5.1

• Additions
  • Added permissions for all commands
• Improvements
  • Rewrote how dead players are handled, reducing lag
  • Rewrote signs, they actually work now :3
  • Added more checks for loading arenas, hopefully fixing errors
  • Save inventories in the world the arena is in, fixing multiworld conflicts
  • Improve leaderboard, now shows player teams
  • Continued to improve messages
  • Continued to work on the API
• Bug Fixes
  • Fixed some NPE's on startup and load
  • Fixed some xp and inventory related bugs
  • Fixed a bug with Essentials compatibility
  • Fixed a bug where players would keep their helmet
  • Fixed a spawning bug with conquest

2.5

• Additions:
  • Added support for potions in classes
  • Added an ingame leaderboard (/ua info)
  • Added countdown with XP bar
• Improvements:
  • Massive amounts of code cleanup and optimization
  • Rewrote how logged out players are handled
  • Fixed and rewrote potions, inventory handling, and items in general
  • Rewrote force start command
  • Added cash reward for MOB arena
  • Standardized messages and teleportation
  • Rewrote help command
  • Officially updated to 1.6.2, although nothing changed
• Bug Fixes:
  • Fixed the infamous MultiKill bug
  • Fixed KOTH arena not working
  • Fixed spawning errors with certain arenas
  • Fixed errors with SPLEEF ground
  • Fixed multiple message errors
  • Fixed some NPE's and CME's
  • Fixed bug that would end multiple arenas at once

If games are ending instantly, this is a 1.5 bug! Mojang changed the way health was handled! Update to 1.6 if at all possible!
If you are getting Essentials related errors, update to their latest build! Essentials has been making some API related changes recently!

Other than that, none :)

As always, create a ticket or comment if you find one.