Skills such as list, documents, workflow, permissions... are a bit too basic and are requirement for a SharePoint DEVELOPER.
I'd argue that perhaps site (and site structure) is an area that would fall under the architect's plate.
There are more areas that a SharePoint architect can help with:
Capacity planning - running multiple servers in a farm. Scalability and other magic words.
Knowing the capabilities and business scenarios of using SharePoint - this is a very common one.
The manager asks: what can SharePoint do for me?
The developer asks: well, what do you want it to do.
The manager then asks: well, I don't know what it can do for me so how do I know what do I want it to do?
Closely related to SharePoint capabilities are the various licensing costs related to each component.
As well as familiarity with development and customization costs. Take the same project time that would have taken in ASP.NET, then multiply it by a large coefficient, and then add an additional constant.
And closely related to what-can-it-do, and how-much-does-it-cost, is the all important question of Return-Of-Investment. All hail supreme ROI!
SharePoint deployment can be a massive issue and a lot of pain.
SharePoint upgrade from v2 (MOSS 2003) to v3 (MOSS 2007). We should be seeing a new version of SharePoint in 2010(?). Well soon after the next version of Office goes out the door. So past upgrade experiences may be useful.
Knowledge of 3rd party webparts. I believe a SharePoint architect should be able to give you at least 5 webparts that they've tried from CodePlex and tell you what they think about them. These are free and easy to grab and play at your own leisure.
Some knowledge of commercial webparts. Because they are still cheaper than writing your own.
Have at least 5 SharePoint blogs that they follow religiously (know the community). If not having their own SharePoint blog (give back to the community).
If they are on StackOverflow they must try to answer SharePoint questions (such as this one).
Attend local SharePoint usergroups. I think communities are a huge deal. Especially what you'd learn from talking with people directly and learning what they are doing with their SharePoint installation. You may just surprise yourself.
Experiences with SharePoint Integration - this comes in two equally important flavours - both from SharePoint accessing existing systems (business catalogs, webparts, etc), as well as other systems accessing SharePoint content via webservice or API.
In addition, SharePoint works with (or works well) with Office, OCS, reporting services, performance point, project server.
SharePoint hosting arrangements - Microsoft SharePoint online services can be a popular and cheaper option to start using SharePoint. It can be hosted inhouse, or with a 3rd party company. Knowing the options is always useful.
Must have read SharePoint code using reflector (and preferably still having hair).
I think it takes at least a couple of years to be a SharePoint architect (your mileage may differ). Your .NET architects need to want-to-be a SharePoint architect, otherwise I agree with other's summaries before me - find someone who already is a SharePoint architect.