First of all many thanks to all at letsencrypt, this is a huge leap forward for open source and free software.
I have a working letsencrypt certificate on my site.
The certbot docs imply that apache versions greater than 2.4.8 will accept a combined certificate and key file. I am running apache 2.4.10 on a debian jessie server and tried the single file approach, but it failed. I replaced the single SSLCertificateFile pointing to fullchain.pem with separate SSLCertificateFile and SSLCertificateKeyFile pointing to cert.pem and privkey.pem and all was well.
That's not quite correct - apache >= 2.4.8 will accept a combined cert + chain file (called fullchain.pem with certbot), not a cert + key file. Older versions of apache need a separate SSLCertificateFile (pointing to cert.pem) and SSLCertificateChainFile (pointing to chain.pem) directive for the chain certificate. The SSLCertificateKeyFile directive pointing to privkey.pem is always needed.
Also, what docs are you referring to precisely? B/c if you’re saying something is incorrect there, it would be helpful if you actually linked the page in question