Using Slate's delegate counter and the most recent state-by-state poll numbers (where they exist), I calculate that the remaining 982 delegates apportioned by primary will break 496-486 for Obama. That would give him 1,688 primary and caucus delegates, leaving him 337 short. And, he already has pledges from 201 superdelegates, cutting the number needed to 136 (under my calculations). As the uncommitted superdelegates are extremely unlikely to vote counter to the will of the voters in their states, he would almost certainly get at least that many. (Today, 279 superdelegates are uncommitted.)
Now, that's using my methodology, which is hardly scientific: I based my numbers on current polls, which are bound to change. But, I gave Clinton the benefit of the doubt whenever I could, and always gave her most of the undecided voters. In any case, it's a reasonably educated guess about where things stand today.
The wild cards are, of course, the Michigan and Florida delegations, which right now won't be seated. (They scheduled primaries in violation of party rules, and as result lost their delegates.) Howard Dean wants a do-over, but says the national party won't pay for it. The Clinton campaign wants the faux primary results to count (she won both), but that's unlikely. On the other hand, it's unimaginable that those two states won't have convention delegates, so something will be worked out. Even factoring in Clinton wins (and that's an especially debatable proposition in Michigan), she has not to date won any primary by the kind margins required to surpass Obama. In fact, whatever happens with those two states, he would likely wind up needing less than 100 superdelegates.
All of which explains recent hints from the Clinton campaign that they'd be amenable to a Clinton-Obama ticket. However, there's no reason for Obama to sign up for that. He's ahead, after all. Moreover, recent national polls have him trouncing John McCain, running much more strongly in the general election than Clinton. Despite last Tuesday's setback, he remains in a commanding position. At some point, Clinton must pull off a couple of genuine upsets to change the dynamic. Otherwise, one of the most anticipated campaigns in recent memory will collapse, mostly done in by the weight of its own baggage.