Take a look at MMO-Champion's list of crafted gear... iLevel 359 are the epics in Blacksmithing anyway. That tells me that 359 is the iLevel of blues and purples dropped in Heroics and possibly even the first tier of raiding (so long as the pattern is the same as that in Wrath).

Given the dev's stated goal to have players gear up in heroics before hitting raids, there's no way the gear from raids won't be a tier past the stuff from heroics.

With 333s as the designed entry level for heroics, it's not unlikely that the heroics will drop 346s (possibly all blues; maybe purples off the end boss), with the crafted epics matching the first raid tier at 359. The usual tuning is for an instance to require gear one tier (13 item Levels) below what drops.

If memory serves...

...there was a blue post stating something along the lines that heroics would drop no purples in order to keep purple gear "special" -- either grind it out in with farming rep or raids or farming mats. *shrug*

Apparently we'll be doing our first raids in Blue gear from heroics.