I've checked that again and what I have is:
1. JBoss Tools 2.0.X for Eclipse 3.3 (was built with eclipse 3.3.1.1)
2. JBoss Tools 2.1.X for Eclipse 3.3 (was built with eclipse 3.3.2)
3. JBoss Tools 3.0.X for Eclipse 3.4 (was built with eclipse 3.4.2)
4. JBoss Tools 3.1.X for Eclipse 3.5 (was built with eclipse 3.5.2)
I think JBoss Tools 2.0 and 2.1. might be installed on 3.4 because they have no restriction for eclipse plugin versions in manifest, but I doubt it would work.
But anyway if you have Eclipse 3.5 and JBossTools 2 then update to JBossToos 3 should work for you :)