I've used gravity forms multiple times and all is well. However, in this particular case I am running WP 3.1 RC1 and GF 1.5 RC2 (both downloaded this morning). With GF being the only plugin activated, I try to add a new form which turns out I am unable to do. The initial "From Settings" panel where you give your form a name, details etc is missing. - Screenshot: http://d.pr/lOwR
I can try and add items and they do not show either.
One thing that should be noted is I previously had the site as a multi-site with Gravity Forms network enabled. Since then I decided to go back to a single site. I'm guessing WP 3.1 RC1 and GF 1.5 RC2 normally work just fine together so this is the only "odd ball" situation I could think of at the moment that could possibly cause a glitch.
Thanks,
Luke