Question is in the title. Has something to do with Sharepoint, but a little bit of searching on my part didn't turn up a good answer.
The IIS WAMREG admin COM+ service component that you're referring to is part of IIS web application manager (WAM) functionality. Basically, WAM allows IIS to work with processes that it doesn't specifically host itself but with which it needs to interact (or even start). WAM provides the interprocess communication (IPC) mechanism between IIS-hosted processes and those that are not hosted by IIS.
There isn't a whole lot of documentation on it readily available, but you can at least see a glossary mention here:
I hope this helps!
The typical reason people care about this in relation to SharPoint is that they start seeing errors in their Event Log relating to the IIS WAMREG admin component. Here is the KB article detailing this: http://support.microsoft.com/kb/920783
The errors do not cause any problems with the functionality of SharePoint, and are basically a nuisance.