Cleaning up the core code, adherring to default PHP coding standards would be a good idea... not only for performance reasons.
Also, the core code should decide what kind of quotes it wants to use... stuff like this is ugly and rather confusing people:
BAD:
/*
echo('bla');
...
echo "bla";
*/
GOOD:
/*
echo("bla");
...
echo("bla");
*/
Get it? ;)
Furthermore, it should be made clear by wordpress if 3rd party sourcecode suggestions are welcome and where someone like me can post/push it so the "wordpress devteam" can check it out.
I'm digging the wordpress pages all over the internet, but I can't find a real answer to this. There is some SVN talk along the way, but no real "one page info" that gives the info short and direct: (1) who is on the core devteam, (2) who should be contacted for sourcecode stuff that just does not fit in the forums, (3) are sourcecode suggestions welcome? and (4) where to post/push the suggested sourcecode if you're not part of the core devteam.
I could propose some more (and probably more valuable things) but I want to see "how interested the devteam is" to get fresh input. I guess it's a give-and-take situation... ;)