I hadn’t even realized (not subscribed to my own feed), but luckily Klaus told me – after my feed had been empty for nearly two months ;)
The funniest thing about this is that my subscriber number stayed pretty much the same – thank you for holding!
There seems to be a known bug in WordPress 2.5.1, but none of the fixes I found worked. While www.gadgetguy.de/wp-rss.php will still give you an empty feed, www.gadgetguy.de/?feed=rss works nicely.
So I disabled my Feedburner Feedsmith plugin (which redirects all the URLs to Feedburner) and updated the Feedburner feed to the working URL.
So, if you want to subscribe to my blog, please use the Feedburner link
Thank you. (not to you, WordPress – grrrrr….)