WHAT ROLEPLAYING IS:
Roleplaying is, to put it simply, pretending. Like an actor, you 'play' the 'role'. The difference between actors and roleplaying gamers lies basically in one key point: gamers don't have a script to follow, unlike most actors. Roleplaying games are basically improvisational theater with rules imposed to prevent utter chaos.

If you ever played Cowboys and Indians (yes, I know that's not PC... so shoot me, I was always an Indian

Another aspect of roleplaying is separation of character and player knowledge. For example, if I'm playing a Drow Cleric in SL, she won't know that all the LA players are going to be taking part in a raid on the Bandit HQ at a certain time just because my LA character was invited to take part. Thus, it would be out-of-character knowledge and I wouldn't use it to schedule a raid on LA. Now, if a Drow assassin had found himself in a position to eavesdrop on some LA characters boasting about how 'the whole faction is going to wipe out the bandits next Tuesday', that's in-character knowledge... and the Last Alliance is probably gonna get pwned.

WHAT ROLEPLAYING ISN'T:
Speaking in the vernacular (also known as Elizabethan English or 'thee speak'). This can be a *part* of roleplaying (i.e., your character always speaks that way because that's how they speak in the world he came from), but it is not necessary. My PnP gaming group does quite well roleplaying while using idiomatic 21st century American English. When used properly, this can add a lot to roleplay: "Thou'rt a craven knave indeed!", to me, sounds better than, "You're just a big chicken!"
Forcing other people to play 'in character'. If someone doesn't want to roleplay, all the shouting in the world won't change that fact. Accept it and move on. If you really want to annoy them, respond as your character would to their questions. "What is my class build? I don't understand your question..."
An unrestricted license for PvP. If you're griefing, you're griefing. The standard rules still apply - and anyone I catch going through my pockets better be able to out-fight or out-run me if they don't want to respawn.

BEING 'IN CHARACTER':
Metagame information, such as class/level, hit points, experience and ability scores are not things that a character has any real knowledge of. In general, you can refer to these things as references: 'Tordek is a warrior who is as strong as an ox and just about as bright. He's only recently come to Aetheria and doesn't remember many of his skills from his old world.' could be used to describe a 16 STR, 9 INT, 1st-level fighter.
Something like 'Suyara is a nimble but not-too-hardy halfling ro... er, scout, who has seen several winters in Evenshire.' to describe an 18 DEX, 8 CON 5th-level halfing rogue. (There's no set period for describing levels unless you want to establish one; LadyCheron and I used to speak of 'seasons', as in "I've been adventuring for 7 seasons" to indicate a 7th level character.)
One can ask for a person's 'profession' rather than his 'class', and you can also give out descriptive text instead of just the class name: "I have the honor to be a humble penitent of Lathander, trying to spread his wisdom and healing light to the dark corners of Aetheria." sounds better than "I'm a cleric with Sun and Healing domains." Metagame information, like a specific build, is better discussed outside of the game. You have access to the boards and the #neversummer irc channel; use them!
IN CONCLUSION:
Roleplaying can add a lot to your Neversummer experience. If you don't feel like doing it, however, you don't have to... and no-one should force you to. But by the same token, you shouldn't try to force someone to NOT roleplay. If all you want to do is log on and kill things, go ahead... but don't get upset when someone asks you, 'What ho, m'lord? Off to slay another ogre, thou sayest! Canst partake of thy glorious adventure?'... it might be me.

Sir Sean, DM Starknight
Oghma, Binder of that which is Known