Wikipedia's declining volunteer base

For many people like me, Wikipedia is the most successful example of opening content creation up to the masses and empowering and motivating volunteers to contribute high quality work. So this recent front page story from the WSJ is interesting, and a little troubling:

Volunteers have been departing the project that bills itself as "the free encyclopedia that anyone can edit" faster than new ones have been joining, and the net losses have accelerated over the past year. In the first three months of 2009, the English-language Wikipedia suffered a net loss of more than 49,000 editors, compared to a net loss of 4,900 during the same period a year earlier ...

As a few people from Wikipedia point out, the decline in the number of participants isn't necessarily a bad thing; the real question is, are entries and quality and usefulness to readers continuing to go up? Maybe a smaller number of participants can do this better than the earlier (or current) large number. But at the very least, the numbers and anecdotes suggest that the organization needs to do a better job attracting, or not scaring off, new participants -- especially among women, people over 35, and tech novices.