PHPMyAdmin has released the last series of PHPMyAdmin which supports PHP4, 2.11.0. The next series will drop PHP 4 support and will only works with PHP 5 and newer. It's one of their decision, since they are one of the many application developers who supported Go PHP5 campaign, which promotes the use of PHP 5 instead of PHP 4. Btw the way, the life cycle of PHP 4 will end this year, so start migrating your code to PHP 5 since you still have about 3 months to do so.
It's also expected that web hosting provider will upgrade their PHP version to PHP 5, so start noticing your client now and give them time to switch to PHP 5 compatible before running the upgrade. I still saw a lot of Indonesian web hosting provider that used older version of PHP 4 series. Perhaps they don't want to disrupt the operation of the sites that were hosted on their servers, but it's quite important to do so.