No, I didn't have to buy anything.
I wanted the Pro version so that I could learn more about DC's and Layout to see if it would be worthwhile upgrading to Pro on the student machines - the jury is still out on that one

I'm based in the UK and it didn't seem to cause a problem.
Should have said though that this is a one year licence.
This link gives all of the details
http://sketchup.google.com/industries/edu/educators.html

watkins, if you are an educator - in Google parlance- you can get a free version of Pro 7 for your own use. I got mine from Journey Ed , you just need to provide them with some form of 'academic proof'. e.g. staff id/payslip/letter from principle whatever.

This is set of images I put together as a demo for one of our students. It is not identical to the plough but I think you could probably apply the same sort of technique.
The final part is done with Booltools but you could use 'intersect with model' if you don't have the plugin

wing.skp

Not sure if this is what you want, but a trick I picked up (from here ?) is to draw a rectangle around the shape then delete the unwanted bits - you'll have top ungroup your lines first

Pew End2.skp

I've been trying to find some easy way for my students to add surface detail to their models and hit on the of using dingbats as 3d text - no doubt you've all done this before but I thought it was quite neat.
Anyway, this is a quick Podium render of an experimental piece using a celtic dingbat font

I like the shadow detail in this and thought it could have other uses

I'm a UK based teacher and have been searching for almost a decade for some effective way of introducing CAD to our students. Over the years we have tried numerous CAD packages from pro-desktop (supposedly designed for school use), through Autocad and onto Solidworks (hey we even dabbled in Maya for a few terms ).
In every case it was the learning curve that defeated me/us.

While the older students could persevere, practice and end up with a reasonable skills set. The younger ones couldn't even get started and became frustrated and bored with the software.

Then along came Sketchup. I'm afraid I must admit that on my first encounter I was in the same camp as your lecturer friend . Yes its all very good, but it is a bit limited and it is not proper CAD'. So I put it away along with a pile of other software and set about the Solidworks video tutorials - yet again.

This summer while mooching around the net, two sites opened my eyes - Podium and this forum. I suddenly realised that my initial impressions of sketchup were mistaken, that that simple interface belies a very sophisticated and capable CAD package. What is more I soon realised that if I a science based teacher with no formal art/design training and limited graphical skills could produce some reasonable models within a few days. Then I could teach all of my students to do so.

Since then, unfortunately I've become a bit of a Sketchup evangelist and I'm sure the art/design staff and students are becoming a bit tired of my ' have you thought about using sketchup for this', gambit Still they're very tolerant and almost always do take up my offer of training.

Interestingly, the comments I always hear are 'I never knew that you could do so much with it'; 'I never knew that you could make such accurate drawings' and renders from Podium and latterly Hypershot really do seal the deal

So O.K. Sketchup doesn't have some of the whistles and bangs of solidworks et. al. but from my point of view I can think of no better package which not only provides an easy introduction to the world of design and 3D CAD but also has enough depth to allow students to produced design and studies all the way to Advanced level and beyond.

Hypershot makes a nice job of rendering these.
This is just a preview - so a few artifacts

Attached is a basic file made up from items from the warehouse.
If you use interact tool you can switch between and empty and full table

To see how it works, go to Component Attributes and switch on formula view- notice how the custom variable 'empty' is referenced in the 'items' attributes i.e. table!empty

Essentially it is as thomthom has described

table.skp

As a teacher (and user of the free version) I probably come at sketchup from a different viewpoint. For me, new tools like interact ( have a look at the mailbox component ) and dynamic components open up lots of new possibilities and will further help to motivate my students.

If I were a professional user,however, I would be very disappointed with this new release, which feels much more like 6.5 rather than 7.

'4/10 Google , after a promising start you seem to be coasting, let us hope you'll make much better use of your talents over the next semester'

If you are in an iso view you can sometimes switch orientations (for both the rotate and angle guide tools) by moving the cursor(pointer) around the view window then pressing the shift key to lock it

So if the cursor is near the bottom the orientation is blue; near the top right green; top left red.

Weirdly this only works in some orientations of the view - bug? feature? who knows.

I came across this the other day which might be useful, though I haven't had a a chance to try it out yet

(www.archvision.com)