As announced in news today, Pingbacks have arrived on LiveJournal! For the time being, this feature is limited to Paid Accounts. More information can be found in the FAQ.
Here is how it works: your entry (as Paid user) is linked to by another (Paid) user. As long as both entries are public, and you have your comment settings set so that you can receive comments from all registered users, you will receive a screened comment from pingback_bot showing you the link to your entry. All comments by pingback_bot will be screened, regardless of your account settings - you can choose to unscreen them if you wish. Pingbacks to and from Paid Accounts can also be sent to and from any blog that supports the Pingback protocol. If you would like external sites to interact with your entries through Pingbacks, you'll need to change your default setting for Pingbacks to "Open".
1. First, make sure that you and the person linking to your entry are both Paid users and that both entries are public. The default setting for Pingbacks will be "LiveJournal.com only," but you can check or change that on the Privacy tab of your Account Settings page.
2. Make sure your comment settings allow comments from either "registered users" or "everybody" and that you have your CAPTCHA setting for comments on "anonymous commenters" or "nobody".
3. Wait 15 minutes - this is the amount of time needed for the Pingback system to check and deliver the ping. If you don't see the comment from pingback_bot, comment here with a link to the entry that didn't get the pingback. Developers will monitor the comments here and we hope to have this issue resolved as soon as we can.
View Friends Page by Date works in S1
In December, we announced the Paid feature View Friends Page by Date. At that time, it was not compatible with journals using the S1 Style System due to the fact that S1 had been retired and deprecated. In January, developers investigated and created a fix - so if you're still using S1 you can now view your friends page by date to your heart's content!