In CTP2 of PowerShell v2, we added a new parameter to Get-Help: Online. This parameter lets help authors declare an “online version” of their help topic, which PowerShell then launches with your default browser. For the PowerShell cmdlet help topics, we redirect to the excellent (and more frequently updated) online cmdlet help topics: http://technet.microsoft.com/en-us/library/dd347701.aspx.

PowerShell supports online help content for both MAML-based help topics (http://msdn.microsoft.com/en-us/library/bb525433(VS.85).aspx, http://blogs.msdn.com/powershell/archive/2006/09/14/Draft-Creating-Cmdlet-Help.aspx, http://blogs.msdn.com/powershell/archive/2008/12/24/powershell-v2-external-maml-help.aspx) and inline help comments (http://technet.microsoft.com/en-us/library/dd819489.aspx.)

To add support for the –Online parameter to your own cmdlet help, add a maml:navigationLink element with a maml:uri node to the maml:relatedLinks section in your MAML help. The help system uses the first navigation link that contains a URI as the target for the link.

maml:relatedLinks
              maml:navigationLink
                     maml:linkTextOnline version:</maml:linkText>
                     maml:urihttp://go.microsoft.com/fwlink/?LinkID=113279</maml:uri>
              </maml:navigationLink>
(…)
</maml:relatedLinks>

When writing comment-based help, use the .LINK tag for the same effect:

## .SYNOPSIS
## Gets an object from the system
## .LINK
## http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx
function Get-MyObject
{
    "Hello!"
}

For more information about this feature, see Get-Help Get-Help –Parameter Online.