It depends on the kind of bug you are referring to...
Your device could have a P.T.D. (Phone Transmitted Disease)
Does it have funny bumps all over it that weren't there before?
It could be "Phono"...
the little known relative to to the kissing sickness...Mono ...
and of course there is always the worst case of Mono...
Double-Mono...otherwise commonly known as ..Stereo....

You really should do the "sit-down" talk with your n900 ..
Ask it where it's been going out at night,
And who the "other" phones are ..it's been hangin' around with lately...
It is treatable ...
But in the future..
Always practice safe maemoing...
Use a phone condom...

Ok....[sigh] ...I suppose I should at least be a little serious and actually properly answer the question to your satisfaction.
in short and brief...[I prefer boxers myself...ok ...back to serious..]
No...we don't really have a virus prob. ...the odd time possible vulnerabilities ... solvable...but yeah...no ...no viruses ...

win. phone, droid, ipone...they got probs...high profile...they have the prominence of market share and numbers of users across the planet..hence will have a higher malware / viral risk......plus ...lotsa suckers..who don't know anything nor really want to know anything about their devices... waiting to be hit by bad, bad, bad stuff.
Sooooo...there it is DarthNokia...
come ...join the dark side...[Dibs! Said it to him 1st! ]