Way up over 3e. Yes, starting characters are tougher, but so are the monsters. Plus, monsters of any level actually pose a threat now since they are on par with PCs for HP, AC, and powers/abilities.
In the game I'm a player in, we've just finished Keep on the Shadowfell, and had five deaths in it. Oddly enough, Irontooth wasn't one where we had any deaths, but several PCs down and dying. The battle outside the waterfall killed one PC, the hobgoblin boss took one PC to -35 HP, the gelatinous cube killed 2 PCs, and drowning trap killed another. Almost every encounter has PCs down and dying, making death saves, and our group uses GOOD tactics. A group with poor tactics and teamwork would be toast right out of the gates.
In the game I run (which is more Lovecraftian horror with more limited PC healing and resurrections), we've had two deaths in 5 sessions. Again, almost every fight has at least one PC down and dying, and PCs are using very good and creative tactics.
4e is just plain brutal in combat, but my players and I LOVE it!!! We never had this kind of challenge in 3e- things were either a cakewalk, or a TPK- almost no in between. 4e seems to have ratcheted up the lethality, with the attitude "if you're a chump or the mysterious loner type, you're dead meat", which suits me just fine.
