Thanks for asking about this. You're right, errata links are no longer showing up for Make books. We're looking into this, but in the meantime, you can get to the errata page by grabbing the product identifier from the product page's URL and adding that to "http://oreilly.com/catalog/errata.csp...=".
So, for Make Electronics, the product page URL is http://shop.oreilly.com/product/9780596153755.do and the errata page is at http://oreilly.com/catalog/errata.csp?isbn=9780596153755. Let me know if you have trouble tracking down any particular book, and I can get the link for you.
Thanks again for writing us about this,