Get iPhone 3.0 features now!

Well, some of them at least :)

Spotlight
Cydia: Quickgold

Copy and Paste
Cydia: Clippy and hClipboard

Sending multiple photos in Email
Appstore: SendPhotos, Multi-Photo Email

Landscape Keyboard in Mail, SMS, and Notes
Appstore: TouchType and Notes+.
Cydia: BiteSMS.

MMS
Cydia: SwirlyMMS

Improved Stocks Application
Appstore: MadStocks

Turn-by-Turn GPS applications
Cydia: xGPS

Bluetooth
Cydia: iBluetooth

What you can’t currently get
Built in search for Mail, iPod, and Calendar
Support for new calendar types
Stereo Bluetooth A2DP audio - Unless iBluetooth is updated to support this
Maps inside other applications - Jailbroken apps can integrate the google maps API, but currently, Appstore apps cannot.
Push notification - Background jailbroken applications is a similar variation - although uses more battery
And other small, new features not worth mentioning.

More in depth look here:

Get iPhone 3.0 features now iPhone News, Help and Guides: "Get most of the features of iPhone OS 3.0 right now!"