With all the talk about whether Democrats can or should use reconciliation to pass health care, it's worth noting that, in some ways, reconciliation doesn't actually matter: If Nancy Pelosi can somehow wrangle enough votes in the House to pass the Senate bill, then they won't actually need to use reconciliation for the bill to become law. Obama could, and presumably would, simply sign the Senate bill into law, regardless of whether a fix package went through in reconciliation.
Now, House Democrats have expressed repeatedly that they don't like the Senate bill and aren't willing to pass it without revisions. And they've said that, in order to vote for the bill as is, they'd like some sort of signal from the Senate that it will, indeed, pass a set of agreed-upon changes—perhaps a letter signed by 51 Democratic Senators promising to vote for a fix package through reconciliation.
But despite talk about how reconciliation makes Senate passage easier, even with 51 Senate Democrats intent on using reconciliation, it won't be a clear shot: Republicans have the option of using an infinite amendment strategy to delay or perhaps kill the fix package. So presumably what Republicans need to do to stop the bill in the House is to make a credible threat that they will, in fact, do everthing they can to kill the reconciliation fix package, thus making it clear to wavering House Democrats that if they vote for the Senate bill, what they'll get is the Senate bill that they don't like, not a fixed bill.
The problem with this strategy, of course, is that it would put Senate Republicans in the position of voting against a "fix" package to the bill—a fix that, for example, strips out unpopular special deals. That might not look good come campaign season, when Democrats would be able to run on the line that Republican Senator Whazzizname voted to keep special interest deals in the health care bill. Given the difficulty of the vote, it's possible that some Republicans might simply decide that it's better to let the fixes (and thus the rest of the bill) go through and run against health care in November. Making a credible threat to block the fix bill in reconciliation has the best chance of stopping the bill entirely, but it also runs the risk of backfiring.
My understanding is that Senate Republicans are still trying to figure out what they're going to do, and that some of them are only just beginning to understand both the options available and the potential outcomes. With a White House announcement about the strategy to go forward with reform imminent, they'll have to make a choice, and soon.