http://technet.microsoft.com/en-us/library/cc263526.aspx

This article explains the features that work in what browsers, I don't know yet what works with the Mac version of Office 2007.

This list is great, and grouped by type, like Government etc.

http://www.wssdemo.com/Pages/websites.aspx

Yes, you can download a VHD here that will work for 30 days: http://www.microsoft.com/downloads/details.aspx?FamilyID=67f93dcb-ada8-4db5-a47b-df17e14b2c74&DisplayLang=en

You will need Virtual Server R2, 1GB of RAM (2GB is better) and 10GB hard drive space.

The first question is do you want to focus on Configuration or Development? The second is do you want to specialise in MOSS or WSS?

There are two configuration exams:
http://www.microsoft.com/learning/exams/70-631.mspx
http://www.microsoft.com/learning/exams/70-630.mspx

There are also development exams:
http://www.microsoft.com/learning/exams/70-542.mspx
http://www.microsoft.com/learning/exams/70-541.mspx

In both cases there is one for MOSS and one for WSS.

If you pass any of these, you become a MCTS: Microsoft Certified Technical Specialist. This is like an MCP, as it only needs one exam passed to get, but it is a well sought after qualification and pays well:

http://www.itjobswatch.co.uk/contracts/uk/mcts.do

These exams are done through an exam provider like Prometric: http://www.prometric.com

You pay about $140/€100/£70 to sit the exam. There is about 50 multiple choice questions and you have 2-3 hours to do it. The pass mark is something like 70-85% so you have to know your stuff!