Today, 24 March 2008, the student application period opens. And it remains open for a week, until 31 March 2008, presumably at one minute before midnight UTC.
If you haven't already discussed the MySQL related ideas published on forge.mysql.com/wiki/SummerOfCode2008Ideas, do so now.
A good place to first silently lurk in and then actively participate in is lists.mysql.com/soc.
As opposed to last year, you can now also apply for MySQL Worklog Items Open for Community Development listed on forge.mysql.com/wiki/ComContribution_Worklog. Worklog items are internal "todo items" or coding tasks identified (but not yet necessarily being actively worked upon) by MySQL AB, ehh, now Sun Microsystems.