This is a serious problem for any TXT record with multiple strings, including records used by many email authentication protocols - SPF, SID, Domainkeys, and others. Here is a simplified example.
# dig txt @open-mail.org example.com.s-id.net +short
"Test 9" "2nd string"
# dig txt @ns1.rimuhosting.com example.com.s-id.net +short
The first record is from our master server, the second from one of several slaves we have set up using PowerDNS. We were planning on using PowerDNS for all our public servers, but this is a showstopper. Many records, especially those for larger domains like aol.com, require TXT records longer than 255 characters. Such records MUST be split into multiple shorter strings.
Indeed, this is a problem. The solution involves telling PowerDNS it should store TXT records differently in memory, and rely on the 'record length' to know when we've seen the last TXT record.
Fixed in commit 996