I have may ideas for projects that require ethernet connection, it's too awkward and expensive to use an ethernet shield.
You can use a serial connection to a PC that has an internet connection and use the PC as bridge. Almost all prog languanges on a PC support serial ports so ...
The netduino plus has ethernet but I'm not sure that I want to use .NET.
FEZ is also a .NET based solution, that is (more or less) hardware compatible with Arduino shields. www.tinyclr.com
Is an Arduino version planned with ethernet on board?
There are arduino compatible boards with wifi - http://asynclabs.com/store?page=shop.product_details&flypage=flypage.tpl&product_id=23&category_id=11&vmcchk=1
Can the netduino plus be programmed with the Arduino programming environment including the ethernet hardware?
Not afaik, it is a completely different software platform that has similar hardware pin layout
Edit: Should have posted this in Development, sorry