How to detect first or last iteration of apex:repeat

I rethought and this seems the best way so deleting the previous contents:

1. Create a map<account,index>

2. Put the account, index and also populate the last index in your method, and check if the index = last index and render the ,

Page:

<apex:page controller="testing_repeat_controller" sidebar="false">
<apex:repeat value="{!Itemsforuser}" var="item">    
    <apex:outputPanel >
        <apex:outputText value="{!item.Name}"/>
        {!IF(account_index_map[item] == lastindexofaccount,'',',')}
    </apex:outputPanel>
</apex:repeat>
</apex:page>

Controller:

public class testing_repeat_controller {
    public integer indexofaccount {get;set;}
    public integer lastindexofaccount {get;set;}
    public map<account,integer> account_index_map {get;set;} 
    public testing_repeat_controller(){
        indexofaccount      = 0;
        lastindexofaccount  = 0;
        account_index_map = new map <account,integer>();
    }
    public List<account> getItemsforuser(){
        list<account> acc_list = [select id,name from account limit 10];
        lastindexofaccount = acc_list.size();
        for(account a: acc_List){        
            indexofaccount = indexofaccount +1;
            account_index_map.put(a,indexofaccount);
        }
        return acc_List;
    }
}

Output:

abc ,abc ,TEST ,test123 ,abc ,abc ,abc ,TEST ,Test_Pass ,abc

I think a more elegant solution would be to render items as an unordered list and then use css to render the commas.

<style type="text/css">
    .cs-list {
      display: inline;
      list-style: none;
      padding-left: 0px;
    }

    .cs-list li {
      display: inline;
      margin-left: 3px;
    }

    .cs-list li:after {
      content: ", ";
    }
    .cs-list li:last-child:after {
        content: "";
    }
</style>

...
<ul class='cs-list'>
<apex:repeater var='item' value='{!myStringList}'>
   <li>{!item}</li>
</apex:repeater>
</ul>

You might need to tweak margin and padding a bit to get it to look perfect (this example came from an project that was loading bootstrap css).