OK folks, today’s top stories are a new Mac Pro replacing the PowerMac, and lots of preview nuggets from OS X 10.5.

First off, it’s bye bye PowerMac, hello Mac Pro. It’s a 64-bit computer with dual 2.66GHz Core 2 Duo “Woodcrest” processors, a 128-bit vector engine, 4MB shared L2 cache, two optical drives, Superdrive, gig’o'RAM, and roughly twice the speed of of its predecessor.

There’s less cooling required in the box, which frees up space for more drives, up to a terabyte of storage if you need it. The outside of the case stays the same, but the interior is all new; you can insert drives by just clicking them into place, no tools necessary.

All this (and more, much more if you explore the build-to-order options) for $2499, shipping today.

There’s also some new Xserves to play with, five times faster than before according to Apple, including dual Xeon chips and with room inside for an optional redundant power supply or plenty more storage. And $2999 for the basic spec machine.

Switching the entire Mac product line to Intel has taken just 210 days.

Jobs used his keynote to say “Thank you” to the developer community, which has worked so hard to adjust to the new architecture. Developers have done a “phenomoenal job”.

As for OS X 10.5 Leopard - well, it’s still a work in progress. But it will include support for 64-bit applications, and the ability to run 32-bit apps alongside. Both fully compatible, no emulation or translation needed. The support runs right through the various layers of OS X.

There’s also something called Time Machine, making automatic backups of the system. Every change you make to every file is backed up in the background, to a server or a disk. It’s described as “a whole new way of backing up files” and is reached via the Finder (although it’s open to third-party apps too - lots of exciting potential there). Past versions of Finder windows appear to zoom off into weird black hole; it’s almost like OS X meets the TARDIS.

As expected, Leopard will include Boot Camp and a next generation Front Row, plus an updated version of Photo Booth (with support for external cameras, a great move). And, at long last, virtual desktops known as Spaces.

Spotlight gets a makeover, too. With Leopard, it will be able to search other computers if it has the correct permissions. So you can search all your home network Macs from just one, or search workgroup servers remotely. It will include an easy-to-reach recent items list too.

Another new idea: Core Animation. It makes animating almost anything much easier. Give it a few frames of animation - the beginning and the end, and some stuff in between, and Core Animation fills in all the gaps. Very neat.

There’s a renewed emphasis on accessibility in Leopard, and VoiceOver boasts some great new natural-sounding synthesized voices.

Mail is turning into a productivity app, with todos, notes and stationery added, with plenty of pre-designed templates. The notes feature creates a new mailbox just for personal notes and jottings, keeping them separate from the rest of your messages. Todo items can have priorities, alarms, and can be created from any incoming message. It’s all tied in to iCal, indeed any app can join in the fun. It’s a system-wide todo list. The productivity geeks are going to be going nuts over all this.

Dashboard will benefit from the much-anticipated Dashcode, a new app designed to make widget-making simple. It’s a visual editor for CSS, with useful “parts” ready-made to drag right in to your widget, and a Javascript debugger. Users also get to play with it too; they can use it to turn web pages into simple widgets.

A new version of iChat includes tabs (hooray!), video recording features, multiple logins and lots more. You’ll be able to use iChat to share a presentation or photo slideshow, and conduct your own commentary over it too. And - oh wow - iChat lets you use any photo or video has a backdrop for your video chat. Go see the demo already, it’s impressive.

A developer preview is available from today, but the full release will not be until next Spring.

Now, what’s the saying? Oh yes: Redmond, start your photocopiers!