This is one of the greatest disadvantages from Pentax.
The new digital bodies don't symchronise with TTL Pentax Flashes, as well as the Digital lenses can't be put onto an analog Pentax.
You can find information at Pentax forum of the : http://www.dpreview.com.
Only Pentax *istD has a good cooperation with both TTL and P-TTL flashes.
I am interested in buying a Pentax *istD only for this reason.
Pentax got into the marketing games that Canon did, betraying their customers. Every new lens you buy does not operate with analog bodies or future bodies (with full frame CCD).
My advice for everyone Pentaxian "DON'T BUY PENTAX LENSES WHICH ARE NOT COMPATIBLE WITH ALL THE PENTAX BODIES AND DON'T BUY ANY NEW BODY WHICH IS NOT COMPATIBLE WITH LENSES OR FLASHES OF THE PAST".
If you do it Pentax will change the formats and will make you change continuasly your equipment. This is very ennoying.
Finally only Nikon respects their customers.
So, if you are thinkig of changing branch, this is the opportunity to do it.

In 1994 I wanted a camera in order to use it for a project of my faculty. I had to take photos in a monastry of Holy Mount Athos. I didn't have much money and all I had was little experience on Zenith SLRs.
During that period I saw a used Pentax P30T with a Pentax cheap lens 28-80/3.5-4.5 in a shop. I didn't resist in the temtation and I bought it. I got in love with that camera. Later, I got a Tamron SP 35-210/f3.5-4.2. I became a strong Pentax supporter.
My dream was to get the (P)Z-1(p). This dream became reality, after 3 or 4 years. I didn't want to lose my P30T, but I had to because I didn't have the money to buy my Z1.
Soon, I loved my Z1 so much that I have still been refusing leaving the film. If there was a hand-grip for this camera. I wouldn't ever leave it.
I hope that Pentax K1d will be sth like Z1 with full of accessories.