P2Pool.org is now running jtoomim's fork of P2Pool. The stats page on P2Pool.org is therefore now tracking jtoomimnet's stats, not mainnet's stats.

If you're mining on mainnet, your miner stats will no longer appear on P2Pool.org's stats page as long as windpath continues running jtoomim's fork. This does not mean your shares on mainnet have been lost, just that P2Pool.org is no longer keeping track of mainnet and its miners' stats. If you're looking for your miners' mainnet stats, you would have to look at the web frontend of another mainnet P2Pool node.

If your miner is pointed at P2Pool.org's node, you would now be mining on jtoomimnet. It would take some time for your miner to ramp up to its expected amount of shares on jtoomimnet, while your mainnet shares would start to fall off the mainnet sharechain. This would, in theory and in general, have limited impact on your expected earnings during your miners' transition from mainnet to jtoomimnet.

(I'm assuming that you are not running and mining at your own P2Pool node, and that you were relying on P2Pool.org's stats page for your miners' stats.)