After updating to Akismet 2.5.0 I had to fall back to Akismet 2.4.0 on 4 different WordPress (3.0.3) powered sites (all single, non-multi) due to version 2.5.0 not showing the graphs/pie when viewing Akismet Stats. All 4 sites are running the same, regularly updated plugins that have been running for 4 years now ("standard" type plugins, nothing weird or obscure). All previous versions of Akismet have worked properly.
I understand that updating to WordPress 3.0.3 is tied to Akismet 2.4.0 but does that mean that version 2.5.0 is not fully compatible with WP 3.0.3? It certainly seems that way at least with the graphs/pie not showing under the "Spam, Ham, Missed Spam, False Positive, Yummy Pie" tabs.
Edit: I also tested out Akismet 2.5.0 in a test site using the nightly builds of 3.1 (via the Beta Tester plugin) and, with no other plugins activated, 2.5.0 is exhibiting the same problem as seen in WP 3.0.3. No graphs/pie are showing when viewing Akismet Stats.