I've been wanting to display the SKU on the Product Info page too. I'm sure there's many ways but here's one for products that don't have multiple variants.
In the file ProductInfo.ascx add a literal to display the SKU (i.e. the new literal being the bold part of the following code:
<h3 class="productname">
<asp:Literal ID="lProductName" runat="server" />
</h3>
<br />
<asp:Literal ID="lSKU" runat="server" /><br />
<div class="shortdescription">
Now the the code behind file, ProductInfo.ascx.cs, add the following code after the line lFullDescription.Text = product.FullDescription; (line 62 approx):
if (product.HasMultipleVariants == false)
{
ProductVariant thisVariant = ProductManager.GetProductVariantByID(product.ProductVariants[0].ProductVariantID);
lSKU.Text = string.Concat("[Part No: ", product.ProductVariants[0].SKU , "]");
lSKU.Visible = true;
}
else
{
lSKU.Visible = false;
}
Recomplie, upload the new files and dlls from the bin and this will display the SKU on the product info page for products with only a single variant. You can mess with css to change the style and I'm going to tweak it to include multiple variants but this does me for now.
Hope it helps.