I am using DNN for my work and think it is absolutely the right solution for that environment.  I am wanting to do a private venture and create a site where people can create their own page, "yahoo" or "myspace" style and upload photos and stuff and have some minimal content editing capabilities, not admin.  My questions are:

1. Is DNN the right solution for this environment? 
2. Would the best way to do this be create a page for the user or a portal (with limited editing for certain modules)
3.  What are the advantages and dissadvantages of each, is there a portal or page limit?  What if I had 1000 users creat a page or portal, is it going to slow my site down.

Any advice would be appreciated.  Thanks in advance!

You would not want to give a user too many rights. There fore every default control panel in DNN could not be used (to expose to your users)

You would need to write custom control panel acoording to what you want to allow. Remeber DNN is a framework, not a solution. It contains all building bloks you would possibly need, the default interface actually limits your possibilities too much.

You would write a module so a user could manage his tabid, including adding modules and configuring them.