Why is OCS and Communciator 2007 better than Windows Live Messenger

I just saw a really great blog post by Darren Strange on this subject. They raise some really good points about why you would use one over the other in a business scenario.  They break their comments down to a few areas:

 - Integration with AD, Exchange and SharePoint
- Security
- Higher fidelity presence
- Phone integration
- Enterprise management

It really is worth a read so check it out