The K20D official brochure is available in Germany now:
http://www.pentax.de/downloads/photo/de/Pentax K20D/SLR_Catalogue_K20D_GER.pdf
Some guy at DPR did a quick translation and comparison w/ K10D:
Changes from predecessor (K10D)
• 14,6 Megapixel (effective)
• 2,7’’ screen with a resolution of 230.000 Dots
• Live View
• Sensitivity ISO 100 to ISO 6400
• Custom Image with 4 colour profiles
• 36 programmable custom functions
• Flash PC-sync connector for studio flash
• Picture sequence in Burst-Mode with 20 pictures per second (1.6MP JPEG)
• Finer Graduations/Levels (not sure what they mean by Abstufungen) in JPEG
• White balance bracketing
From the text, further differences/news:
New dust warner, showing a shot of the sensor with dust spots on the screen.
Better dynamic range (one stop more).
Recommended kit price with new 18-55 II: 1299 Euros
EDIT! New stuff from catalogue pdf
1. 35mm MAcro goes to 1:1
2. RAW button switches between RAW, RAW+JPEG, only JPEG and becomes more configurable
3. integrated intervall timer! (up to 99 shots, 1s to 24h apart)
4. user can define file names!
5. TFT screen can be colour-adjusted!
6. digital preview now allows saving of the previewed shot - even with adjusted WB!
7. Bracketing does 3 or 5 shots (only 3 on K10D)
8. The new long lenses will be available at the same time as the K20D, maybe even the 35mm limited