Wired Intelligent Edge

Hi as subject, is the switch 2620-48-PoE+ stackable?

Not in the real sense of the word, no.

The 2620s stackable option allows you to manage multiple switches from one IP address, but this not to be confused with stacking which utilises the switchs backplane, like Cisco Cat 3750s and Nortel 4550 etc.  Each 2620's ports are independant of the next 2620 switch in the stack, so you can not trunk connections across two 2620 switches that are in the same stack. Hope that makes sense :)

So what you probably want are the brand new 2920 switches released this week. They definitely are stackable, in the true MLAG sense.