management is too broad a term.
It really depends on what you want to be able to do from one place. And, it also depends on how you originally set up your WP sites.
I do not have any experience with this, but have been putting a fair bit of thinking into the best way to set up the WP farm I plan on having by the year end.
For example, there is a trivial method to have all your WP blogs run on one codebase with one database. The only differentiator is the table prefix. This makes it easy for example, to do things like upgrades and backups. Upgrade script once, it feeds to all sites running on that codebase. Also, back up entire database in one go. Any plugins and themes that save configurations to the DB and not filesystem will work nicely with this. It does though, require all your blogs to be on one server.
Adverts. Rather than set up individual adverts on each blog, you are better off just defining your zones on the blog/template. Serve and track your ads from your own ad server. Download openX, and set that up on a different domain, and use that to manage the ads each blog is serving.
Traffic. Ditto for traffic monitoring. Install Piwik, and use that to track traffic across your blog empire.
Posting. If you are not autoblogging, you could use email to post to your blogs. Setting up an email account for each blog is trivial. After that, just email the new post and it gets published. Alternatively you could set your blogs to publish from RSS feeds, and then set up one MotherShip blog that pumps out custom RSS feeds to each blog in your empire. Similarly, there are plugins (I think), that will check a folder for any txt files, and publish those as posts.
Etc etc etc. I could go on about my proposed direction
There are 3 key things that drive my thinking in this regard
1. Platform independent. I don't want to be locked into one vendor to manage my blogs. The above means I run everything myself
2. Not breaking upgrades. Again, none of the methods above requires gutting any of the existing WP code. That means that each blog can still function as an independent entity, should you for example, decide to sell it off. At the same time, It means that you do not break WP, and can easily keep up with upgrades to the core or to plugins without further ado.
3. Scaleable. Done right, there is no limit to the number of blogs you can easily manage remotely. You can add and remove WP blogs from the setup at will. Take the ads. Assuming you had a juicy CPA offer. You could, with OpenX, push it to all your blogs with one click.
4. Free *I know I said 3*, but yey, you get this one free
. None of the above you will cost you money.
YMMV
