As I recently upgraded from WP2.7 to the 2.8-branch, some issues could be expected.
A recurring issue concerns a plugin I’m using to display those lovely popups (lightbox) to display images without leaving the page. Long story short: it’s not working anymore.
I’m currently looking into a solid replacement, but so far no luck. You’ll have to do with the non-lightboxed images I guess. 
NEW: I’ve added Slimbox to this site, to get the boxes back. Thanks EER!
Hey Maarten,
Welcome back to the blogging front!
Try slimbox.
Hey EER, good hint!
Slimbox is nearly there when it comes to being a complete substitution of my old lightbox-thingy, yet it lacks some things.
For example, all images on a page are put into the very same ‘gallery’. My old one split the images in a per-post gallery.
The animations are slightly more cumbersome by default, yet that would be adjustable. Unfortunately, this is not achieved by modifying a value on my website, it involves altering some sourcecode. Less usable.
However: it will be powering my website from now on, until a better alternative pops up.
Thanks!
You’re welcome
I’ll keep my eyes open on my internet adventures and let you know if I stray across something