The List is not final yet, please give comments, I will updated the comparison
Another update (thanks for Brit and Alexander)
    Team Foundation Server (TFS) SubVersion( open source)
Requirement Hardware One server, less than 20 users.
Application and data tier server single processor, 2.2 GHz
8 GB Harddrive,
1 GB Memory
any pc is fine
Software Requirement Supported Windows 2003 server any operating system
Other Software Requirement SQLServer 2005
Windows SharePoint Services
ASP.NET/IIS
.NET Framework 2.0
None
   
   
  Linux Support  
    NA Yes
   
  Source Code Control    
  Check in/out Yes Yes
  Shelving Yes Yes
  Branching Yes Yes
  Work Item association Yes No
  Check in policy Yes ???
  Work Item Yes ???
  Unit Testing Yes ???
  Clean Build Yes ???
  Code Analysis Yes ???
  Custom Yes ???
  Check in notes Yes Yes
     
     
  Web based Source access    
  Web based interface N/A
not available for this version.
Can create custom UI to grap data from database
Yes
     
  Work Items    
  MSF defined (i.e, "bugs", "task","scenarios",etc) Yes Trac
  Custom/3rd party defined Yes Trac
  Link to tests Yes Trac
  Link to builds (Team Build) Yes Trac
  Link to source files (Team Foundation Server SCM) Yes Trac
     
     
  Reporting Services    
  "Out of the box" Reports Yes Trac
  Bug List Yes Trac
  Bug Rates Yes Trac
  Builds Yes Trac
  Code Coverage Details Yes Trac
  Dev and QA Work Yes Trac
  Exit Criteria Status Yes Trac
  Issues Yes Trac
  My Bugs Yes Trac
  Quality Indicators Yes Trac (from excel export)
  Quality Velocity Relationships Yes Trac(from excel export)
  Remaining Work Yes Trac(from excel export)
  Test Result Details Yes Trac(from excel export)
  Work Item List Yes Trac(from excel export)
     
     
  Project Management    
  Microsoft Office Integration Yes N/A
  Process Template Yes N/A
  MSF Agile Yes N/A
  MSF for CMMI Level Improvement Yes N/A
  Custom/3rd party templates Yes N/A
  Project Portal Yes Gemini
  Report Web Parts Yes N/A
  Bug List Yes Gemini
  Bug Rates Yes Gemini, Trac
  Builds Yes Ant
  Code Coverage Details Yes Gemini, Trac
  Dev and QA Work Yes Gemini, Trac
  Exit Criteria Status Yes Gemini, Trac
  Issues Yes N/A
  My Bugs Yes N/A
  Quality Indicators Yes Trac, Gemini
  Quality Velocity Relationships Yes N/A
  Remaining Work Yes Trac, Gemini
  Test Result Details Yes N/A
  Work Item List Yes  
     
  Team Builds    
  Build Team Projects (multiple Visual Studio Solutions) Yes Ant
  Generate "Builds" Report Yes Ant
  Run and report Code Analysis Yes ???
  Run and report test results Yes ???
  Calculate code churn between builds Yes ???
 
 
  Offline Features N/A Yes