I just bought my Pen a week ago, and I love it so much!  I definitely want to get a zoom lens for it, but I need to get more information first.  At first the 300mm with an adaptor seemed like the most logical choice, but I read that the 150mm is the equivalent to the 300mm.  Is this true?  What are the pros and cons of both?  I found the 300mm on Amazon for $267 with free shipping, and the adaptor for $139.  Combined that is cheaper than the $599.99 sticker for the 150mm.  But I don't want to pay that much for something that doesn't work very well.  I'd rather go for higher cost and higher quality.  Can someone please shed some light on this for me? 

I think getting a zoom that tops out at 150-200 should suffice for many people. Going to 300mm (which is a 600mm equiv in 35mm terms) is a bit much, unless you're into wildlife or astrophotography.

The 14-150 zoom for $599 (which is what I assume you're referring to) offers many advantages for its hefty price: a true super-zoom that covers wide angle and telephoto, and a quick and silent internal focus mechanism that makes it ideal for videos. Contrast this to, say, a 100-300 zoom, which is easier to manufacture and cheaper to buy, but is much less useful in every day use, IMO.

You could also consider getting an adapter for some of the older 4/3 lenses. They're much cheaper and offer a much more diverse range.

Good point. And I just noticed that bhphotovideo.com has the 4/3 40-150mm AND the adapter for just US$ 200. That's bang for the bucks!

i saw that deal too it great...199 for 40-150 and oly af adapter

also consider the 45-200 panny with lens based ois which works very well
its aboutr 300 dollars , i love it

bang for the buck is also provided by an excellent 50 mm slr lens which will make a great portrait lens 100 equiv fov .... that is actually more accurate to pinpoint manual focus and adapters have gotten very cheap and with a 10 dollar set of extension tubes doubles as a superb image quality macro lens  ..........BANG!!!$$$$

it sounds like you're fairly new to photography, if thats the case the 14-150 oly or the 14-140 panny are the lenses that are gonna make you the happiest. If you buy a 70-300 your not gonna be able to take pics of groups or landscapes and might easily feel frustrated. Play around with something with a more familiar range first the move to the specific lens (macros, super wide angles and extreme telephoto).