<p>I have strange problem with sharepoint and ajax functionality. We have an UpdatePanel placed inside webpart. When partial postback occurs, page title gets missing.</p>

<p>We have found that temporary partial solution is to write title element into one line and not use any spaces or controls inside it..not even a literal control.</p>

<p>But we need some way to provide sommon title for all pages, so title would look like this:
My default title - Current page title</p>

<p>Any ideas how to solve this?</p>

this looks like pure sharepoint's problem..also it looks like just sites based on publishing page layout are affected.
I debugged response in firebug and for some reason it returns setting for page title, so response from server contains not just update panel information, but also empty page title.
I debugged our webparts and none of them plays with page title. I would suggest not to use publishing or just not use any controls inside title.
We are currently working on this issue in company i work for, so i'll upload uour findings when we figure out something.