... but. I found myself in exactly the same position not so long ago. I was a member of a medium-sized development team (25+ people) which had no management at all. The result was that various people from different parts of the organization were giving us tasks and nobody really knew who they reported to. Yes, it was a mess and I would often bitch and moan about it - I could afford that because I was on friendly terms with the top management.

Then one day something karmic happened: I was told I was becoming the manager of that team. As I didn't have a manager to look to for example, I had to learn somewhere else. So I went to Amazon and I bought every book on the subject which looked promising in the reviews. Here's my top 5 in order of preference:

1. Peopleware
2. Managing Humans
3. Joel on Software
4. The Art of Project Management
5. Up the Organization

Beware of number 5 - not everything applies to software development teams, but it's a good books nevertheless.