There is an arcgis data server produce that does not require SDE. It serves SQL 2008 geometry directly. If you do not mind writing code, check out the sql server 2008 add on package which include the .NET library for spatial type.
You will first need to get the data into a web browser. You can write a simple .NET Webservice or PHP script that will server features. What you will want to do is to 'massage' the data returned by SQL into the ESRI Rest format. Check out the ESRI Rest Specification, if you can serve data in the same format you can feed it straight into a feature layer, using a feature collection or maybe straight from the url if you want to implement Query,Identify etc in your little map service.