The evolution of browsers
Still, I would prefer browser vendors to go after some low-hanging fruit first. I mean, emerging HTML5 technologies are cool and all, but how about concentrating on the actual HTML part first? How about implementing common forms controls (date/time pickers, rich text editors, improved validation and more)? How about fully implementing CSS Paged Media? How about implementing MathML? How about replacing .pdf with .html first and then focus on killing Flash?
And while we are at it, how about improving bookmark management in Chrome? The current interface leaves a lot to be desired (i.g. multiple categorization of bookmarks using tags and/or hierarchical folders, similar to the categorization available in Google Docs).
In short, I would like to see more pragmatic features sooner rather than later.