I have a Pre coming in the mail from eBay tomorrow, and I want to know the best apps. I'm switching from my DROID until June.
I really like Tweed, it covers most of the bases and fits the webOS interface very well like you mentioned but many other palm users are into Bad Kitty so look them both up.
Facebook chat is coming in the next version of the Fb app, I'm not sure if there is a current solution to that now though..
The engadget app.
Dr. Podder for podcasts, if you have a need for that, I've never used a better podcast client.
Also, you'll probably enjoy your Pre more if you overclock it. PreCentral.net should have a guide.
Engadget recently did their own roundup of the best apps for the platform -
And there was a similar thread on gdgt about the same topic a while back too -