...what does it mean?
At this point in the season, not much. But, the timing of the achievement, of the dramatic victory to reach the number and being in between series provides a good opportunity to take stock of the Pirates season thus far.
With 80% of the season still to go, it's hard to say that the Pirates can sustain their record over the 128 games still to be played. They were definitely going to play .500 ball over a 34 game stretch during the course of the season, so it may just be a coincidence that it occurred during the first 34 games. Maybe their destiny is to stink and the record will adjust itself accordingly as the sample size increases.
On the other hand, if you're looking for a source of optimism, it is that the Pirates rank 7th in team ERA in the NL. Pitching was the biggest cause of concern at the outset of the season and yet it has been the strength of the pitching that has carried us thus far. In particular, it is three Neal Huntington acquisitions who have outperformed their expectations: James McDonald, Kevin Correia and Mr. Electric, Charlie Morton. If you didn't check it out last week, I highly recommend reading Dejan Kovacevic's profile on Morton (part 1 here and part 2 here).
The disappointing other half to the equation would have to be the offense. With high expectations from the young core four, the offense has mostly fell flat, ranking just 11th in the NL in runs scored, though they have been surging in May. An optimists view of that situation might be to think that the offense will eventually start to perform, so maybe we haven't seen the best out of the Pirates yet.
My take on the Pirates thus far? Well, I'm not going to get ahead of myself. The season is still barely a month old and we have a long way to go before getting excited about .500. But, I'm going to enjoy it for as long as it lasts. May looks like a tough month with divisional road matchups against the Brewers, Reds and Cubs, plus series against the Dodgers, Tigers and Braves looming. If they can get to June 1 at .500, then I'll start to get excited.