Things were progressing steadily on the syslog-ng front. About 4 weeks ago I released syslog-ng Premium Edition 2.1.5 which was the first version with integrated SQL support. Since then the first production deployments of PE have been done, shaking out some newly introduced bugs in the process (thus the releases 2.1.5a - 2.1.5d).
Disk buffering works nicely, especially when combined with the new rate-limit option (throttle), if your backend systems are calibrated to a given rate of incoming messages, syslog-ng can ensure that the limit is never exceeded. Whenever bursts end, syslog-ng feeds the messages towards the back-end systems in their idle time. This introduced some latency though.
I've started working on support for the new syslog-protocol work in IETF, but nothing is ready yet. After this is finished, I'm planning to release syslog-ng 2.1 under the GPL license, with some of the new features added.
The GPLd branch also saw a couple of fixes, no release though. If you want the latest set of fixes, please use a daily snapshot.