We have often been asked for comparisons between DotNetNuke, other OpenSource alternatives and proprietary portal frameworks from Microsoft.  The table below is a modified version of that posted by Shaun Walker (MS MVP, ASPInsider, original creator of DNN and author of many WROX books)in DNN Forums.  The table now includes a comparison with ezPublish and some additional changes based on our experience and perspectives.  ezPublish is an alternative Linux (LAMP stack) hosted portal framework. 

The case for DNN vs exPublish is easy- DNN wins based on features, ease of development, price, better developer community and ease of upgrading.  A decision to go down the Sharepoint  or DNN route really depends on what your requirements are.  For some, the decision will be clear-cut.  For other installations, the reasons for choosing one or the other (or even between the various versions and levels of the Sharepoint family) are very subtle;  in our experience it's most often a decision based on prioritisation of the compromises you need to make.  The situation is further complicated by the fact that you can integrate DNN (through modules) with the WSS that comes with Windows Server 2003 which means in some circumstances you don't necessarily need to pay for Sharepoint Portal Server;  contact us for discussion on this.

The price comparison at the end of the table assumes a 1000 seat user base hosted on a medium server configuration and includes only software cost.  

Feature	DotNetNuke®	ASP.NET 2.0	ezPublish  Premium	SPS 2003 and WSS 2.0	MOSS 2007 and WSS 3.0	DotNetNuke® Benefits
Usability
Portal Framework	(Extensible)	(Web Part Framework)	(LAMP- PHP4)	(Proprietary)	(Web Part Framework)	unlimited pages per site, unlimited modules per page, ability to display module on multiple pages
Browser-Based Administration
Intuitive Control Panel
Inline Editing, Drag and Drop
Site Search						Does not depend on third party components or services such as Index Server, etc...
Content Management
Content Import/Export
Templates						site and page templates ( with content ) supported
MS Office Integration
Bundled Functionality
Announcements
Blog
Contacts
Documents
Events
FAQs
Feedback
Discussion Forums
Photo Gallery
Html/Text Content
IFrame
Links
Media
News Feeds
Custom Reports
Directory
Store
Survey
Custom Forms/Tables
Banner Advertising
Newsletters
Event Logging
File Manager
Recycle Bin
Membership & Roles
Plugin Membership Provider						support for all Microsoft Membership Provider attributes
Active Directory Authentication
Internet/Extranet Authentication
Public, Private, Verified Registration Options
Plugin Roles Provider						additional support for Effective Date, Expiry Date, Avatars, Subscriptions, etc...
Security Role Trimming						role trimming control visibility at the Page, Module, and Folder level and also includes extensibility options for adding additional Permission types
User Profile
Plugin Profile Provider
Extensible User Profile System						Profile items can be managed at run-time using an intuitive administrative interface. User interface controls generated automatically for collection of profile data.
Application Extensibility
Integrated Component Architecture	(Modules)	(Web Parts)		(Web Parts)	(Web Parts)
Rapid Development Model	(User Controls)	(User Controls)		(Server Controls)	(User Controls)
Developer Tool Support	(All VS2005 SKUs)	(All VS2005 SKUs)		(VS2003 Pro)	(VS2005 Pro)	supports FREE Visual Web Developer Express 2005 and SQL 2005 Express
Code Generation Templates						uses integrated Visual Studio item templates
Automated Packaging						integrated with standard application
Efficient Distribution						single ZIP file
Run-time Installation						integrated with standard application
Designer Extensibility
Templating Architecture	(Skins)	(Master Pages)		(Themes)	(Master Pages)	pre-compiled for maximum performance and flexibility
Design Tool Support		(VS2005)			(VS2005)	Supports ALL design tools ( PC and MAC )
Automated Packaging						integrated with standard application
Efficient Distribution						single ZIP file
Run-time Installation						integrated with standard application
Site Extensibility
Site Virtualization						supports multiple virtual sites from a single application/database based on URL
Friendly URLs						flexible RegExp URL Rewriting engine
Localization
Resource File Framework
Run-time integrated editor
Scalable						Does not use satellite assemblies ( satellite assemblies can cause memory consumption issues in hosted environments )
Automated Packaging						integrated with standard application
Efficient Distribution						single ZIP file
Run-time Installation						integrated with standard application
Security
Medium Trust Compliant
Document Management
Secure Document Storage						supports storage on file system and in database
Infrastructure
XCOPY Deployment
No IIS Customization
Web Farm Support
Multiple Database Support			(with extensions)
Shared Hosting Optimization
Community
Professional Plugin Ecosystem
Professional Designer Ecosystem
Support Forums
Licensing
License	Open Source		££	£££	£££	licensed under an enterprise-friendly BSD/MIT open source license
Source Code
Pricing
Price	FREE	FREE	>£ 3000 per year (Free  development license)	$40,000	£££

We probably should extend this comparison table to include Community Server 2007 from Telligent which we believe has common features and historical roots with DNN.  The software is available from Telligent run by Rob Howard (another ASPInsider, Site Server guru, MVP, WROX author). Direct price comparison is however not possble without knowledge of your requirements- many useful components are optional licensed extras. It's an expensive licensed product, particularly when loaded with the extras required to compare with DNN.  Definitive selection between DNN, CS2007 and SPS/MOSS will require us to have a better understanding of your requirements; contact us to discuss.