We’ll be using PHP and cURL to retrieve the numbers, and then caching them in the database with WordPress’s get_option() and update_option() functions, so we don’t slow things down or use-up your Twitter API limit.

First, here’s how you get your FeedBurner circulation as plain text:

$fburl="https://feedburner.google.com/api/awareness/1.0/GetFeedData?uri=Webmaster-source";
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $fburl);
$data = curl_exec($ch);
curl_close($ch);
$xml = new SimpleXMLElement($data);
$fb = $xml->feed->entry['circulation'];

Replace Webmaster-source with your FeedBurner ID (the part at the end of your RSS link) and you’re all set. Now you can echo out the $fb variable to display your RSS circulation.

To get your Twitter follower count, you would do something similar:

$twurl="http://twitter.com/statuses/user_timeline.xml?id=redwall_hp&count=1";
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $twurl);
$data = curl_exec($ch);
curl_close($ch);
$xml = new SimpleXMLElement($data);
$tw = $xml->status->user->followers_count;

As with the FeedBurner snippet, replace redwall_hp with your Twitter username, and then you can just echo $tw to get your follower count. This snippet isn’t something you want to use as-is though. Twitter’s API limit would soon kick-in and it would quit working. It needs to be cached.

Now you have two code snippets that can retrieve the two statistics. Now they need to be added up into one number and cached.

Here’s the final function, which you can add to your WordPress theme’s functions.php file:

function my_subscriber_count() {

$subscribers = get_option('my_subscriber_count');

if ( $subscribers['cache_time'] < (mktime() - 3600) ) {

$fburl="https://feedburner.google.com/api/awareness/1.0/GetFeedData?uri=Webmaster-source";
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $fburl);
$data = curl_exec($ch);
curl_close($ch);
$xml = new SimpleXMLElement($data);
$fb = $xml->feed->entry['circulation'];

$twurl="http://twitter.com/statuses/user_timeline.xml?id=redwall_hp&count=1";
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $twurl);
$data = curl_exec($ch);
curl_close($ch);
$xml = new SimpleXMLElement($data);
$tw = $xml->status->user->followers_count;

$subscribers['count'] = $fb+$tw;
$subscribers['cache_time'] = mktime();
update_option('my_subscriber_count', $subscribers);

}

echo $subscribers['count'];

}

Once you add that mess to functions.php, you can display the combined number in plain text simply by putting the following template tag anywhere in your theme:

<?php my_subscriber_count(); ?>

That wasn’t too hard, was it?

If you want to take the FreelanceSwitch route, with multiple counters, the code shouldn’t be too hard to adapt.

Mashable was granted an interview with Steve Olechowski, co-founder of FeedBurner turned Google employee. The Q&A session ended with fifteen answers to frequently asked questions about the transition. Sadly, many of my questions have been left unanswered as of yet.

A very large percentage of the blogosphere uses FeedBurner to cache their feeds, so this topic is one to watch. The service fits well into their business, and should open up some interesting opportunities in the future, and quite possibly the widespread adoption of ads in RSS feeds.

Read the full Q&A at Mashable.com.

Since Google’s acquisition of FeedBurner, Inc. on June 1, 2007, we have been moving the FeedBurner application to Google hardware, software, and data centers. This allows the application to scale and perform like most Google applications and integrate easily with other Google platforms. It also means more reliability in delivering your content, analytics, and monetization, as well as a more secure and consistent experience for your users.

In order to provide an integrated experience and to support the new features we have planned for our feed platform, as well as to improve security, it is necessary for logins to be handled via a Google Account.

Google has set a deadline for you to move your feed now. You have until February 28, 2009 to transfer your feeds. Pro Blog Design has a tutorial on how to do so.

Also, check out Google’s FAQ page for further information.

I decided to take this as an opportunity to compare “normal” feed readers with my own MyNT RSS reader. How? I kept a record of the amount of time it took to read my RSS feeds for a total of one week (using MyNT). Next, I repeated the test with FeedDemon. Here is a chart of the results:

Interesting, isn’t it? The red line represents FeedDemon, and the green MyNT. The dates are 1/6/08 to 1/12/08 for MyNT, and 1/13/08 to 1/19/08 for FeedDemon.

There are things I like about both readers. I really like being able to instantly tell whether a feed has new items in it (a feature not included in MyNT), for example. Really though, I’m not about to switch over from MyNT. I just prefer to read RSS feeds differently than most people (a byproduct of Firefox Live Bookmarks being my first feed reader). Instead, I’m going to keep improving MyNT. I plan to start work on MyNT 2.0 in the near future (read: sometime this year when I have time). Some of the features I’d like to include in MyNT 2 are

• categorical “folders” to organize feeds
• a way of telling whether or not a feed has new items in it (though it would work in a different, possibly better, way than FeedDemon)
• an easier way to find feeds that other users read (a directory of sorts)
• “private” feeds that you must be logged-in to view
• easier feed management

I really want to release a more polished product this time around, a web app that doesn’t feel like it was thrown together in a week (it actually took over a month, working alone, but you get the idea).