The mid-day turnout numbers for today's special election show 1852 voters through noon. There aren't a lot of good turnout comparisons for the district, it looks like it's on track for more than the 2007 city council election, and less than the 2006 governor's election. For what that's worth.
Turnout looks stronger in the North End so far, which figures to be good for Aaron Michelwitz. The four North End precincts account for nearly 40% of the total vote so far, which is far higher than their population accounts for in the district. Chinatown is also turning out relatively well, and Michelwitz has a lot of institutional support there. The South End portions -- where Susan Passoni is thought to have an edge -- are light so far.
None of that is determinant at all, but seems to point to an edge for Michelwitz. However, it's possible that a lot of the early vote was absentee ballots, which may have been collected early from a lot of older North End residents; young professionals in the South End and elsewhere in the district may be apt to vote after work.
So, longish post to say, Who knows? I expected it to be close, and I still do, and it could easily go either way. But I think that that the Michelwitz camp is feeling a tad more comfortable at this stage.