Hey @alex220x,
Smarty 3 provides you with additional information inside the foreach loop, therefore you can use the @index modifier to get the index of the current item:
{foreach $sArticle.sBlockPrices as $blockPrice}
{if $blockPrice@index == 2}
Second element
{else}
...
{/if}
{/foreach}
Best regards,
Stephan Pohl