Developing custom Web Parts which leverage the concept of separating the presentation layer from the control provides you and your customer with great flexibility. Web Parts which produce XML output and render it using an XSL stylesheet given by the end user can be easily reused in multiple projects saving you in some cases some time. While working on the Extended Content Query Web Part I took a look at the performance of the XSL transforms and I have found out that there are thing to be considered while using that concept.
During the Office Developer Conference 2008 I have attended a great presentation on high performance SharePoint 2007 solutions by Andrew Connell. And although I've heard a few times before that if you care for performance of your solution, and obviously you should if you're responsible for delivering Internet-facing Publishing Sites in SharePoint 2007, it became clear to me once again: one of the best aggregation solutions out there you should use is the Content Query Web Part... or isn't it?
Recently I have written an article about the doctypes and SharePoint 2007. My conclusion was that if you're striving to deliver a standards compliant web site built upon SharePoint 2007 you should be using the XHTML doctype. As if delivering an XHTML compliant web site in SharePoint 2007 wasn't challenging enough, there are multiple mime-types which can be used for XHTML compliant web pages.
Defining the natural language of a web page is very important: it allows assistive technologies like screen readers to read the content of a web page out loud using the right accent en pronunciation. In (X)HTML you can define the natural language both for the whole page and particular elements using the lang and xml:lang attributes. As marking a particular fragment of text with a different language isn't really difficult and can be done by the end users, setting the natural language of the whole page dynamically in SharePoint is challenging and must be implemented by developers.
While running through the decks from presentations I have attended at Office Developer Conference I have stopped for a moment on the session given by Andrew Connell on Building High Performance Solutions on Microsoft Office Server 2007. During this session Andrew has presented quite a few methods on optimizing the overall performance of a web site built upon MOSS.