If you haven't yet understood why, let me clarify...
The K2 Community is a very popular site. It's got an Alexa rank of about 10.000 and a 7/10 Google Pagerank. It does a little over 1 million page views per month on average. Spammers love such facts. Not spam bots, actual human spammers.
The past 2 weeks we are being heavily spammed by real human beings with regular Joomla!, Twitter or Facebook accounts (you need a mobile number to get a FB account and bots don't have mobiles). Not mention this has happened again (back when we hosted the community site on the Ning platform which is supposed to have a much better platform to fight spam)... Guess when? When effing Iron Man 2 was released. Spammers love blockbusters.
So what now? We're temporarily disabling new user signups for a few days in order to harden security measures on the site. That includes social logins as well. Fighting real human spam is a very tough situation to deal with. That means we need to add more services like Akismet and extend the integration with StopForumSpam.com to better fight these spammers that have been identified in these huge spammer databases. We also need to improve Kunena's code to allow for quick spam user banning. And since the version of Kunena we're using won't be updated anymore, we're going to get our hands dirty :)
So please bear with us for a few days until we sort the matter. It's a tough call, but I guess it's the price to pay for a popular project.
P.S. If you need to ask a support question and you are not already a K2 Community member, please use Twitter if possible to direct your questions to @k2devs - we'll do our best to answer you there.
Update on May 15th, 2013: We have re-enabled signups to the community.
We were pleasantly surprised today when we read HostGator's blog post on the top 10 Joomla! extensions, ranking K2 as #1 in their list!
HostGator is one of the largest shared hosting companies in the world (part of the Endurance Int'l Group of companies which also owns Bluehost) so it's really an honor for the K2 project to be ranked #1 Joomla! extension according to them. I don't know if this list is just a "snapshot" of what's hot in the Joomla! community or a list based on stats HostGator gathers from hosting probably thousands of Joomla! sites. In any case it's flattering :)
We were actually double-flattered as JoomlaWorks since we were the only company with 2 extensions on this top 10 list. Frontpage Slideshow ranked #6 essentially declared the best slideshow system for Joomla!.
The just released v2.6.5 fixes a couple of nasty bugs found in K2 v2.6.4 which was released last week. These bugs were only spotted when using the new advanced SEF options and the new tag normalization option introduced in v2.6.4.
Although not even 10 days have passed since we released K2 v2.6.3, we decided it would be a shame not to release this new version 2.6.4 ASAP. You see, this new release brings some SEF URL enhancements which we know many K2 users will love. To quickly sum things up we have added the new K2 advanced SEF options, tag normalization options, jQuery 1.8.3 and 1.9.1, improved the transliteration logic introduced in v2.6.3 and removed 2 obsolete online image editors (used via the backend).
K2 version 2.6.3 is now available to download or update, bringing a slight speed boost as well. To quickly sum things up, aside the performance improvements, we're adding jQuery 1.9 support, better transliteration for Joomla! 2.5 & 3.0, Joom!Fish 2.5 compatibity and some SEF router improvements.
K2 version 2.6.2 is now available to download or update. An exciting release as it brings some small but significant improvement to "Extra Fields". Users of version 2.6.0 and 2.6.1 are advised to upgrade as we have addressed lots of minor issues, especially in Joomla! 3.0.
We've just issued version 2.6.1 of K2 which fixes a few minor bugs reported from our users in all Joomla! versions supported by K2.
These bugs are either "notices" popping up in various places in the backend or style related glitches. So far we've sorted what's been reported, but hey, Joomla! released 3.0.1 just yesterday so don't be surprise for a 2.6.2 in the weeks to come ;)...